	SQ-500-SS	SQ-512-SS	SQ-514-SS	SQ-515-SS	SQ-520	SQ-521-SS	SQ-522-SS
Power Supply	Self-powered	5 to 24 V DC	12 to 24 V DC	5.5 to 24 V DC	5 V USB power source	5.5 to 24 V DC	5.5 to 24 V DC
Current Draw	-	At 12 V is 57 µA	maximum of 20 mA	At 12 V is 57 µA	61 mA when logging	1.4 mA (quiescent); 1.8 mA (active)	RS-232 37 mA; RS-485 quiescent 37 mA, active 42 mA
Output (Sensitivity)	0.01 mV per µmol m^-2 s^-1	0.625 mV per µmol m^-2 s^-1	0.004 mV per µmol m^-2 s^-1	1.25 mV per µmol m^-2 s^-1	-	-	-
Output Type	0 to 40 mV	0 to 2.5 V	4 to 20 mA	0 to 5 V	USB	SDI-12	Modbus
Resolution	-	-	-	-	0.1 µmol m^-2 s^-1	-	-
Calibration Factor (reciprocal of sensitivity)	100 µmol m^-2 s^-1 per mV	1.6 µmol m^-2 s^-1 per mV	250 µmol m^-2 s^-1 per mA	0.8 µmol m^-2 s^-1 per mV	Custom for each sensor and stored in the firmware	Custom for each sensor and stored in the firmware	Custom for each sensor and stored in the firmware
Calibration Uncertainty	± 5 %	± 5 %	± 5 %	± 5 %	± 5 %	± 5 %	± 5 %
Measurement Repeatability	Less than 0.5 %	Less than 1 %	Less than 0.5 %	Less than 1 %	Less than 0.5 %	Less than 1 %	Less than 1 %
Long-term Drift per Year	Less than 2 % per year	Less than 2 % per year	Less than 2 % per year	Less than 2 % per year	Less than 2 % per year	Less than 2 % per year	Less than 2 % per year
Non-linearity	Less than 1 % (up to 4000 µmol m^-2 s^-1)	Less than 1 % (up to 4000 µmol m^-2 s^-1)	Less than 1 % (up to 4000 µmol m^-2 s^-1)	Less than 1 % (up to 4000 µmol m^-2 s^-1)	Less than 1 % (up to 4000 µmol m^-2 s^-1)	Less than 1 % (up to 4000 µmol m^-2 s^-1)	Less than 1 % (up to 4000 µmol m^-2 s^-1)
Response Time	Less than 1 ms	Less than 1 ms	Less than 1 ms	Less than 1 ms	Software updates every second	Less than 0.6 s	-
Field of View	180°	180°	180°	180°	180°	180°	180°
Spectral Range	389 to 692 nm ± 5 nm (wavelengths where response is greater than 50 %)	389 to 692 nm ± 5 nm (wavelengths where response is greater than 50 %)	389 to 692 nm ± 5 nm (wavelengths where response is greater than 50 %)	389 to 692 nm ± 5 nm (wavelengths where response is greater than 50 %)	389 to 692 nm ± 5 nm (wavelengths where response is greater than 50 %)	389 to 692 nm ± 5 nm (wavelengths where response is greater than 50 %)	389 to 692 nm ± 5 nm (wavelengths where response is greater than 50 %)
Spectral Selectivity	Less than 10 % from 412 to 682 nm ± 5 nm	Less than 10 % from 412 to 682 nm ± 5 nm	Less than 10 % from 412 to 682 nm ± 5 nm	Less than 10 % from 412 to 682 nm ± 5 nm	Less than 10 % from 412 to 682 nm ± 5 nm	Less than 10 % from 412 to 682 nm ± 5 nm	Less than 10 % from 412 to 682 nm ± 5 nm
Directional (Cosine) Response	± 5 % at 75° zenith angle	± 2 % at 45°; ± 5 % at 75°	± 2 % at 45°; ± 5 % at 75°	± 2 % at 45°; ± 5 % at 75°	± 5 % at 75° zenith angle	± 2 % at 45°; ± 5 % at 75°	± 2 % at 45°; ± 5 % at 75°
Temperature Response	-0.11 ± 0.04 % per C	-0.11 ± 0.04 % per C	-0.11 ± 0.04 % per C	-0.11 ± 0.04 % per C	-0.11 ± 0.04 % per C	-0.11 ± 0.04 % per C	-0.11 ± 0.04 % per C
Operating Environment	-40 to 70 C; 0 to 100 % relative humidity; can be submerged in water up to depths of 30 m	-40 to 70 C; 0 to 100 % relative humidity; can be submerged in water up to depths of 30 m	-40 to 70 C; 0 to 100 % relative humidity; can be submerged in water up to depths of 30 m	-40 to 70 C; 0 to 100 % relative humidity; can be submerged in water up to depths of 30 m	-40 to 70 C; 0 to 100 % relative humidity; can be submerged in water up to depths of 30 m	-40 to 70 C; 0 to 100 % relative humidity; can be submerged in water up to depths of 30 m	-40 to 70 C; 0 to 100 % relative humidity; can be submerged in water up to depths of 30 m
Dimensions	24 mm diameter, 37 mm height	30.5 mm diameter, 37 mm height	30.5 mm diameter, 37 mm height	30.5 mm diameter, 37 mm height	24 mm diameter, 37 mm height	30.5 mm diameter, 37 mm height	30.5 mm diameter, 37 mm height
Mass (5 m of cable)	100 g	140 g	140 g	140 g	100 g	140 g	140 g