Range 0 to 200 ppb Resolution 1 ppb Precision ±5% of reading ±5 ppb @ 25ºC Light Source LED @ 525 nm Light Detector Silicon photocell Environment 0 to 50°C (32 to 122°F); RH max 95% non-condensing Battery Type (1) 1.5V AAA Auto-off After 3 minutes of non-use Dimensions 81.5 x 61 x 37.5 mm Weight 64 g Method Adaptation of Standard Method Ascorbic Acid