Specifications : Battery Life:6 months (typical) @ 5 readings a day / 5 days / week without backlight** ** Backlight usage will decrease battery life. Battery Requirements:4, AA size alkali cells Data Logger:500 measured values (Result, Date, Time, Sample ID, User ID) Detector:Silicon photodiode Dimensions (H x W x D):231 mm x 96 mm x 48 mm Display:Graphical display 240 x 160 pixels (Backlit) Enclosure Rating:IP67 (vial cover closed) Includes:DR 900 Colorimeter, two 1-inch glass sample cells marked at 10, 20 and 25 mL, two 1 cm plastic sample cells, 1 x 16-mm COD/Test 'N Tube adapter, 4 AA alkaline batteries, printed multilingual instrument manual, instrument and procedure manuals on CD, USB Mini to USB Cable, European CE mark. Interface:USB type Mini IP67 Operating Conditions:10 to 40C (50 - 104 F), max. 80 % relative humidity (non- condensing) Operating Humidity:max 90 % relative humidity (non-condensing) Operating Mode:Transmittance (%), Absorbance and Concentration Operating Temperature:10 to 40 COptical System:0 / 180 deg transmittance Photometric Accuracy: 0.005 Abs @1.0 ABS Nominal Photometric Linearity: 0.002 Abs (0 - 1 Abs) Photometric Measuring Range:0 to 2 Abs Power Supply:4 x AA size alkaline cells 4x NiMH rechargeable Battery* (*External charger required) Reproducibility: 0.005 Abs (0 - 1 A) Sample Cell Compatibility:1 inch round or 16 mm round (with adapter) Spectral Bandwidth:15 nm filter bandwidth Storage Conditions:-30 to 60 C (-30 - 140 F), max. 80 % relative humidity (non-condensing) Supported Chemistry:Hach testsTemperature Range:0 to 50 C (32 - 122 F) Wavelength Accuracy: 1 nm (fixed, varies with model) Wavelength Calibration:N/A Wavelength Range:420 nm, 520 nm, 560 nm, 610 nm Wavelength Selection:Automatic Weight:1.32 lbs. (0.6 kg) with battery