Benchtop conductivity meter LD-LBCM-A11

Conductivity measurement range : 0 - 20.0, 200.0, 2000 µS / cm, 200.0 mS / cm

Conductivity accuracy : ± 1 % F.S.

Conductivity resolution : 0.01, 0.1, 1

Conductivity calibration solutions : 10 µS / cm , 84 µS / cm, 1413 µS / cm, 12.88 mS / cm, 111.8 mS / cm

Benchtop Conductivity Meter LD-LBCM-A13

Conductivity measurement range : 0.000 μS/cm to 3000mS/cm

Resistivity measurement range : 5.00 Ω·cm to 100.0 MΩ·cm

TDS measurement range : 0.000 mg/L to 1000g/L

Salinity measurement range : 0.00 to 8.00 %

Benchtop Conductivity Meter LD-LBCM-A14

Conductivity Mode :

Benchtop Conductivity Meter LD-LBCM-A15

Conductivity Range : 0.01 to 20.00, 200.0, 2000 µS/cm, 20.00, 200.0 mS/cm

Conductivity Accuracy : ±0.5 % F.S.

Conductivity Resolution : 0.001/0.01/0.1/1, automatic

Conductivity Calibration : Points    1 to 3 Points

Benchtop Dissolved oxygen meter LD-LBDO-A10

Dissolved oxygen range : 0.0 to 20.0 mg / L (or ppm)

Dissolved oxygen accuracy : ± 0.5 mg / L

Resolution : 0.1 mg / L

Calibration points : 1 - 2 points

Benchtop Dissolved oxygen meter LD-LBDO-A11

Dissolved oxygen range : 0.0 to 20.0 mg / L (or ppm)

Dissolved oxygen accuracy : ± 0.2 mg / L

Resolution : 0.01 mg / L

Calibration points : 1 - 2 points

Benchtop Ion meter for Cl, LD-LBIM-A10

Ion measurement range : Cl range: 5 × 106 - 1 M, 1.8 - 35500 ppm

Ion measurement accuracy : ± 0.5 % F.S.

Resolution : 0.001, 0.01, 0.1, 1

Calibration points : 2 to 5 points

Benchtop Ion meter for F, LD-LBIM-A11

Ion measurement range : F range: 1 × 106M – saturation, 0.02 ppm to saturation

Ion measurement accuracy : ± 0.5 % F.S.

Resolution : 0.001, 0.01, 0.1, 1

Calibration points : 2 to 5 points

Benchtop Ion meter for Na, LD-LBIM-A12

Ion measurement range : Na range: 1 × 105 - 1 M, 0.1 - 23000 ppm

Ion measurement accuracy : ± 0.5 % F.S.

Resolution : 0.001, 0.01, 0.1, 1

Calibration points : 2 to 5 points

Benchtop Ion meter for Ca, LD-LBIM-A13

Ion measurement range : Ca range: 5 × 107 - 1 M, 0.02 - 4000 ppm

Ion measurement accuracy : ± 0.5 % F.S.

Resolution : 0.001, 0.01, 0.1, 1

Calibration points : 2 to 5 points

Benchtop Ion meter for Br, LD-LBIM-A14

Ion measurement range : Br range: 5 × 106 - 1 M, 0.4 - 79900 ppm

Ion measurement accuracy : ± 0.5 % F.S.

Resolution : 0.001, 0.01, 0.1, 1

Calibration points : 2 to 5 points

Benchtop Ion meter for NH₄, LD-LBIM-A15

Ion measurement range : NH4 range: 5 × 106 – 1 M, 0.1 – 18000 ppm

Ion measurement accuracy : ± 0.5 % F.S.

Resolution : 0.001, 0.01, 0.1, 1

Calibration points : 2 to 5 points

Benchtop Ion meter for NH₃ , LD-LBIM-A20

Ion measurement range : NH3 range: 1 × 106 - 1 M, 0.02 - 17000 ppm

Ion measurement accuracy : ± 1 % F.S.

Resolution : 0.001, 0.01, 0.1, 1

Calibration points : 2 to 5 points

Benchtop Ion meter for Cn, LD-LBIM-A21

Ion measurement range : Cn range: 5 × 106 – 0.01 M, 0.2 – 260 ppm

Ion measurement accuracy : ± 1 % F.S.

Resolution : 0.001, 0.01, 0.1, 1

Calibration points : 2 to 5 points

Benchtop Ion meter for Ag, LD-LBIM-A22

Ion measurement range : Ag range: 1 × 107 - 1 M, 0.01 - 107900 ppm

Ion measurement accuracy : ± 1 % F.S.

Resolution : 0.001, 0.01, 0.1, 1

Calibration points : 2 to 5 points

Benchtop Ion meter for K, LD-LBIM-A23

Ion measurement range : K range: 1×106 - 1M, 0.04 -39000 ppm

Ion measurement accuracy : ± 1 % F.S.

Resolution : 0.001, 0.01, 0.1, 1

Calibration points : 2 to 5 points

Benchtop Ion meter for S, LD-LBIM-A24

Ion measurement range : S range: 1×107 - 1M, 0.003-32100 ppm

Ion measurement accuracy : ± 1 % F.S.

Resolution : 0.001, 0.01, 0.1, 1

Calibration points : 2 to 5 points

Benchtop Ion meter for Pb, LD-LBIM-A25

Ion measurement range : Pb range: 1×108 – 0.1M, 0.2-20700 ppm

Ion measurement accuracy : ± 1 % F.S.

Resolution : 0.001, 0.01, 0.1, 1

Calibration points : 2 to 5 points

Benchtop Ion meter for I, LD-LBIM-A26

Ion measurement range : I range: 1×108- 1M, 0.06 -127000 ppm

Ion measurement accuracy : ± 1 % F.S.

Resolution : 0.001, 0.01, 0.1, 1

Calibration points : 2 to 5 points

Benchtop Ion meter for Cu, LD-LBIM-A27

Ion measurement range : Cu range: 1×108 - 1M, 0.06-6400 ppm

Ion measurement accuracy : ± 1 % F.S.

Resolution : 0.001, 0.01, 0.1, 1

Calibration points : 2 to 5 points

Benchtop Ion meter for Cd, LD-LBIM-A28

Ion measurement range : Cd range: 1×106– 1M, 0.01-11200 ppm

Ion measurement accuracy : ± 1 % F.S.

Resolution : 0.001, 0.01, 0.1, 1

Calibration points : 2 to 5 points

Benchtop Multi-parameter Water Quality Meter LD-LMPWM-A30

pH Mode : pH range -2.00 to 20.00 pH pH Accuracy ± 0.002 pH pH Resolution 0.1/0.01/0.001

mV Mode : mV Range -1999.9 to 1999.9 mV mV Accuracy ± 0.2 mV mV Resolution 0.1/1 mV, sele

Conductivity Mode : Conductivity Range 0.01 to 20.00, 200.0, 2000 µS/cm, 20.00, 20

Benchtop Multi-parameter Water Quality Meter LD-LMPWM-A31

pH Mode : pH range -2.00 to 20.00 pH pH Accuracy ± 0.002 pH pH Resolution 0.1/0.01/0.001

mV Mode : mV Range -1999.9 to 1999.9 mV mV Accuracy ± 0.2 mV mV Resolution 0.1/1 mV, sele

Conductivity Mode : Conductivity Range 0.01 to 20.00, 200.0, 2000 µS/cm, 20.00, 20

Benchtop Multi-parameter Water Quality Meter LD-LMPWM-A32

pH Mode : pH range -2.00 to 20.00 pH pH Accuracy ± 0.002 pH pH Resolution 0.1/0.01/0.001

mV Mode : mV Range -1999.9 to 1999.9 mV mV Accuracy ± 0.2 mV mV Resolution 0.1/1 mV, sele

Conductivity Mode : Conductivity Range 0.01 to 20.00, 200.0, 2000 µS/cm, 20.00, 20

Benchtop Multi-parameter Water Quality Meter LD-LMPWM-A40

pH Mode : pH range -2.00 to 20.00 pH pH Accuracy ± 0.002 pH pH Resolution 0.1/0.01/0.001

ORP Mode : mV Range ± 2000 mV mV Accuracy ± 0.2 mV mV Resolution 0.1 mV, selectable

Ion Mode : Ion measurement range 0.01 to 30000 ppm, mg/l, mol/l, mmol/l (refer Range of

Benchtop Multi-parameter Water Quality Meter LD-LMPWM-A41

Benchtop Multi-parameter Water Quality Meter LD-LMPWM-A42

Benchtop Multi-parameter Water Quality Meter LD-LMPWM-A43

pH Range : -2.000 to 20.000 pH

pH Accuracy : ±0.002 pH

pH Resolution : 0.001 / 0.01 / 0.1 pH, selectable

pH Calibration Points : 1 to 5 points

Benchtop Water hardness meter LD-LBWM-A10

Water hardness range : 0.05 mmol / L -0.2 mol / L

Accuracy : ± 1 % F.S.

Calibration points : 2 to 5 points

Calibration solution : 0.001, 0.01, 0.1 mmol/L, 0.001, 0.01, 0.1 mol/L

BOD Meter LD-LBOD-A10

Determination range : 0 to 35 mg/L, 0 to 70 mg/ L, 0 to 350 mg/L, 0 to 700 mg/L (without dilution) 0 to 4000 mg/ L (need to dilute) (subsecti

Measurement error : Less or less than 10 %

Sample container/ bottle quantity : 1 to 6

Sample container/ bottle Capacity : 1000 ml

COD Analyzer LD-LCDA-A10

Measuring principle : Dichromate colorimetric method

COD range : 0.0 to 1500 mg/L

Basic accuracy : ≤ 150 mg/L: ± 8% reading ± 1 mg/L≥ 150 mg/L: ± 8% reading

Repeatability : 3% reading

Pocket Conductivity tester LD-LPCT-A10

Conductivity measurement range : 1.0 to 199.9 µS/cm

Type of conductivity : Low range conductivity

Conductivity accuracy : ± 1 % F.S.

Conductivity calibration points : 1 point

Pocket Conductivity tester LD-LPCT-A11

Conductivity measurement range : 10 to 1999 µS/cm

Type of conductivity : Mid-range conductivity

Conductivity accuracy : ± 1 % F.S.

Conductivity calibration points : 1 point

Pocket Conductivity tester LD-LPCT-A12

Conductivity measurement range : 0.1 to 19.99 mS/cm

Type of conductivity : High range conductivity

Conductivity accuracy : ± 1 % F.S.

Conductivity calibration points : 1 point

Pocket Dissolved oxygen tester LD-LPKDO-A10

Dissolved oxygen range : 0.0 to 20.0 mg/L (or ppm)

Dissolved oxygen accuracy : ± 0.5 mg/L

% of saturation of oxygen : 0.0 to 200.0%

Sensor type : Polarographic dissolved oxygen probe

Multi parameter water quality analyzer LD-LMWA-A10

Multi parameter water quality analyzer LD-LMWA-A11

Online Conductivity Controller LD-LOCC-A10

Conductivity measurement range : 0.01 to 20.00, 200.0, 2000 µS/ cm, 20.00, 200.0 mS/ cm

Conductivity calibration points : 1 to 3 points

Conductivity accuracy : ±1 % F.S.

Conductivity resolution : 0.001/ 0.01/ 0.1/ 1

Online Dissolved Oxygen Controller LD-LODC-A10

Dissolved oxygen range : 0.0 to 20.0 mg / L (or ppm)

Dissolved oxygen Calibration points : 1 - 2 points

Dissolved oxygen accuracy : ± 0.5 mg / L

Dissolved oxygen resolution : 0.1 mg / L

Online pH Controller LD-LOPC-A10

pH measurement range : 01.00 to 15.00 pH

pH calibration points : 1 to 3 points

pH Buffer Solutions : USA (pH 4.01, 7.00, 10.01) or NIST (pH 4.01, 6.86, 9.18)

pH accuracy : ± 0.01 pH

Pocket ORP tester LD-LPOT-A10

Sensor type : Platinum sensor

Connector : 6 pin

ORP measurement range : (-999) to 999 mV

ORP accuracy : ± 2 mV

Pocket ORP tester LD-LPOT-A11

Connector : BNC

ORP measurement range : (-999) to 999 mV

ORP accuracy : ± 2 mV

ORP resolution : 1 mV

Benchtop pH meter LD-LBPM-A10

pH measurement range : 0.00 to 14.00 pH

pH accuracy : ± 0.05 pH

pH resolution : 0.01 pH

Calibration points : 2 points

Benchtop pH meter LD-LBPM-A11

pH measurement range : 0.00 to 14.00 pH

pH accuracy : ± 0.01 pH

pH resolution : 0.01 pH

Calibration points : 2 points

Benchtop pH meter LD-LBPM-A20

pH measurement range : -1.00 to 15.00 pH

pH accuracy : ± 0.01 pH

pH resolution : 0.01 pH

Calibration points : 1-3 points

Benchtop pH meter LD-LBPM-B10

pH measurement range : -2.000 to 20.000 pH

pH accuracy : ± 0.002 pH

Calibration points : 1-5 points

Calibration solutions : USA, NIST, DIN or user defined

Benchtop pH Meter LD-LBPM-B11

Temperature compensation : 0 to 100°C, 32°F to 212°FManual or Automatic

Hold function : Manual or automatic endpoint detection

Stability criteria : Standard or High-accuracy

Interval readings : 10, 30, 60 seconds, 10, 30 minutes or Off

Portable pH meter LD-LPRPM-A10

pH range : (-2.00) to 16.00 pH

pH accuracy : ± 0.01 pH

pH resolution : 0.01 pH

Calibration points : 2 points

Portable pH/ORP meter LD-LPRPM-A11

pH range : (-2.00) to 20.00 pH

pH accuracy : ± 0.002 pH

pH resolution : 0.1, 0.01, 0.001 pH

Calibration points : 1 - 5 points

Pocket pH tester LD-LPPT-A10

pH measurement range : 0.0 - 14.00 pH

Shape of electrode : Round glass pH electrode

pH measurement accuracy : ± 0.1 pH

Calibration point : 2 points

Pocket pH tester LD-LPPT-A11

pH measurement range : 0.0 - 14.00 pH

Shape of electrode : Flat pH electrode

pH measurement accuracy : ± 0.1 pH

Calibration point : 2 points

Pocket pH tester LD-LPPT-A12

pH measurement range : 0.0 - 14.00 pH

Shape of electrode : Long distance planar pH electrode

pH measurement accuracy : ± 0.1 pH

Calibration point : 2 points

Pocket pH tester LD-LPPT-A20

pH measurement range : pH range: (-1.00) to 15.00 pH

Shape of electrode : Round glass pH electrode

pH measurement accuracy : ± 0.01 pH

Calibration point : 1 - 3 points

Pocket pH tester LD-LPPT-A21

pH measurement range : pH range: (-1.00) to 15.00 pH

Shape of electrode : Flat pH electrode

pH measurement accuracy : ± 0.01 pH

Calibration point : 1 - 3 points

Pocket pH tester LD-LPPT-A22

pH measurement range : pH range: (-1.00) to 15.00 pH

Shape of electrode : Long distance planar pH electrode

pH measurement accuracy : ± 0.01 pH

Calibration point : 1 - 3 points

Pocket pH tester LD-LPPT-A30

pH measurement range : pH range: (-1.00) to 15.00 pH

Shape of electrode : Round glass pH electrode

pH measurement accuracy : ± 0.01 pH

Calibration point : 1 - 3 points

Pocket pH tester LD-LPPT-A31

pH measurement range : pH range: (-1.00) to 15.00 pH

Shape of electrode : Flat pH electrode

pH measurement accuracy : ± 0.01 pH

Calibration point : 1 - 3 points

Pocket pH tester LD-LPPT-A32

pH measurement range : pH range: (-1.00) to 15.00 pH

Shape of electrode : Long distance planar pH electrode

pH measurement accuracy : ± 0.01 pH

Calibration point : 1 - 3 points

Multi purpose Pocket pH tester LD-LPPT-B10

pH measurement range : pH range: (-1.00) to 15.00 pH

Shape of electrode : Different electrodes can be connceted via BNC Connector

pH measurement accuracy : ± 0.01 pH

Calibration point : 1 - 3 points

Portable Dissolved oxygen meter LD-LPRDO-A10

Dissolved oxygen range : 0.0 to 20.0 mg / L (or ppm)

Dissolved oxygen accuracy : ± 0.5 mg / L

Resolution : 0.1 mg / L

Calibration points : 1 - 2 points

Portable dissolved oxygen meter LD-LPRDO-A11

Dissolved oxygen range : 0.0 - 20.0 mg / L (or ppm)

Dissolved oxygen accuracy : ± 0.2 mg / L

Resolution : 0.01 mg / L

Calibration points : 1 - 2 points

Portable Multi-parameter Water Quality Meter LD-LMPWM-A10

Portable Multi-parameter Water Quality Meter LD-LMPWM-A11

Portable Multi-parameter Water Quality Meter LD-LMPWM-A20

Portable Multi-parameter Water Quality Meter LD-LMPWM-A21

pH mode :

Portable water hardness meter LD-LPWM-A10

Water hardness range : 0.05 mmol / L - 0.2 mol / L(CaCO3) 0 - 19999 mg / L, (CaO) 0 - 11220 mg / L, (boiler) 0 - 400 mmol / L, (Ca) 0 - 8020 mg / L(German degree) 0 - 1122

Accuracy : ± 1 % F.S.

Calibration points : 2 to 5 points

Calibration solution : 0.001, 0.01, 0.1 mmol / L, 0.001, 0.01, 0.1 mol / L

Pocket Salinity tester LD-LPST-A10

Salinity measurement range : 0.00 to 10.00 ppt

Salinity accuracy : ± 1 % F.S

Conductivity range : 0 - 20.00, 200.0, 2000 µS/cm, 20.00 mS/cm

Calibration solutions : 84 µS/cm, 1413 µS/cm, 12.88 mS/cm

Pocket Salinity tester LD-LPST-A11

Salinity measurement range : 0.00 to 80.00 ppt

Salinity accuracy : ± 1 % F.S

Conductivity range : 0 - 200.0 µS/cm, 100 - 2000 µS/cm, 20.00 mS/cm

Calibration solutions : 1413 µS/cm, 12.88 mS/cm, 111.8 mS/cm

Pocket TDS tester LD-LPTS-A10

TDS range : 0.5 - 100.0 ppm

TDS accuracy : ± 1 % F.S.

TDS factor : 0.4 to 1.0 (default 0.5)

Calibration points : 1 point

Pocket TDS tester LD-LPTS-A11

TDS range : 5 - 1000 ppm

TDS accuracy : ± 1 % F.S.

TDS factor : 0.4 to 1.0 (default 0.5)

Calibration points : 1 point

Pocket TDS tester LD-LPTS-A12

TDS range : 0.05 - 10.00 ppt

TDS accuracy : ± 1 % F.S.

TDS factor : 0.4 to 1.0 (default 0.5)

Calibration points : 1 point

Multi-range pocket TDS tester LD-LPTS-A20

TDS range : 0 - 20 ppt

TDS accuracy : ± 1 % F.S.

TDS factor : 0.1 to 1.0 (default 0.5)

Calibration points : 1 - 3 points

TSS Meter LD-LTSS-A10

Measurement range : 20000 mg/L 0.01 mg/L ~ 45000 mg/L 0.01 mg/L ~ 120000 mg/L

Measurement accuracy : ± 2 % F.S. of its range( Depending on the homogeneity of sludge)

Pressure range : ≤ 0.4 Mpa

Flow rate : ≤ 2.5 m/s, 8.2 ft./s

TSS Meter LD-LTSS-A11

Measurement Range : 0 to 1000 mg/L

Resolution : 1 mg/L

Accuracy : ±5%

Display : 54.38 x 54.38 LCD with backlighting

Portable Turbidity Meter LD-LTM-A10

Measuring range (NTU) : 0 to 200

Minimum readout value (NTU) : 0.1

Calibration point : Nil

Sample volume : 5 to 10 ml

Portable Turbidity Meter LD-LTM-A11

Measuring range (NTU) : 0 to 100,0 to 200

Minimum readout value (NTU) : 0.01, 0.1

Calibration point : 4

Sample volume : 5 to 10 ml

Portable Turbidity Meter LD-LTM-A12

Measuring range (NTU) : 0 to 100,100 to 400

Minimum readout value (NTU) : 0.01, 0.1

Calibration point : 5

Sample volume : 5 to 10 ml

Portable Turbidity Meter LD-LTM-A13

Measuring range (NTU) : 0 to 100,100 to 500

Minimum readout value (NTU) : 0.01, 0.1

Calibration point : 6

Sample volume : 5 to 10 ml

Portable Turbidity Meter LD-LTM-A14

Measuring range (NTU) : 0 to 100,100 to 800

Minimum readout value (NTU) : 0.01, 0.1

Calibration point : 6

Sample volume : 5 to 10 ml

Portable Turbidity Meter LD-LTM-A15

Measuring range (NTU) : 0 to 100, 100 to 1000

Minimum readout value (NTU) : 0.01, 0.1

Calibration point : 7

Sample volume : 5 to 10 ml

Portable turbidity meter LD-LTM-A16

Light source : LED/860 nm (Wavelength)

Readings display : LCD

Unit switches : NTU, FTU, EBC, ASBC

Measurement range : 0.00-20.0; 20.01-200; 200.01-1000 NTU

Portable turbidity meter LD-LTM-A17

Light source : LED/860 nm (Wavelength)

Readings display : LCD

Unit switches : NTU, FTU, EBC, ASBC

Measurement range : 0.00-10.00; 0.00-100.00; 0.00-1000.00; 0.00-4000.00 NTU

Bench top Turbidity Meter LD-LTM-B10

Measuring range (NTU) : 0 to 100

Minimum readout value (NTU) : 0.01, 0.1

Calibration point : 1

Sample volume : 5 to 10 ml

Bench top Turbidity Meter LD-LTM-B11

Measuring range (NTU) : 0 to 50, 0 to 100, 0 to 200

Minimum readout value (NTU) : 0.01, 0.1

Calibration point : 3

Sample volume : 5 to 10 ml

Bench top Turbidity Meter LD-LTM-B12

Measuring range (NTU) : 0 to 50, 0 to 100, 0 to 200, 0 to 400

Minimum readout value (NTU) : 0.01, 0.1

Calibration point : 4

Sample volume : 5 to 10 ml

Bench top Turbidity Meter LD-LTM-B13

Measuring range (NTU) : 0 to 50, 0 to 100, 0 to 200, 0 to 400, 0 to 800

Minimum readout value (NTU) : 0.01, 0.1

Calibration point : 5

Sample volume : 5 to 10 ml

Bench top Turbidity Meter LD-LTM-B14

Measuring range (NTU) : 0 to 50, 0 to 100, 0 to 200, 0 to 400, 0 to 800, 0 to 1000

Minimum readout value (NTU) : 0.01, 0.1

Calibration point : 6

Sample volume : 5 to 10 ml

Bench top Turbidity Meter (with built-in printer) LD-LTM-C10

Measuring range (NTU) : 0 to 100, 0 to 200

Minimum readout value (NTU) : 0.01

Calibration point : 2

Sample volume : 18 to 20 ml

Bench top Turbidity Meter (with built-in printer) LD-LTM-C11

Measuring range (NTU) : 0 to 100,0 to 200,0 to 500

Minimum readout value (NTU) : 0.01

Calibration point : 3

Sample volume : 18 to 20 ml

Bench top Turbidity Meter (with built-in printer) LD-LTM-C12

Measuring range (NTU) : 0 to 10,0 to 100,0 to 200,0 to 500

Minimum readout value (NTU) : 0.001

Calibration point : 4

Sample volume : 18 to 20 ml

Bench top Turbidity Meter (with built-in printer) LD-LTM-C13

Measuring range (NTU) : 0 to 10,0 to 100,0 to 200,0 to 500,0 to 1000

Minimum readout value (NTU) : 0.01

Calibration point : 5

Sample volume : 18 to 20 ml

Bench top Turbidity Meter (with built-in printer) LD-LTM-C14

Measuring range (NTU) : 0 to 10, 0 to 100, 0 to 200, 0 to 500, 0 to 1000

Minimum readout value (NTU) : 0.001

Calibration point : 5

Sample volume : 18 to 20 ml

Bench top Turbidity Meter (with built-in printer) LD-LTM-C15

Measuring range (NTU) : 0 to 10, 0 to 100

Minimum readout value (NTU) : 0.001

Calibration point : 2

Sample volume : 18 to 20 ml

Water Activity Meter LD-LWAM-A10

Measuring range    Water activity : 0 to 0.980 aw (no condensing)

Temperature range : 0 to 50°C

Measurement accuracy : ± 0.015 aw

Temperature accuracy : ± 0.5°C

Water Activity Meter LD-LWTM-A10

Range : 0 to 1.0 aw

Resolution : 0 to 1.0 aw

Accuracy : ± 0.02 aw

Sensor : Nonconductive humidity sensor