Product Parameters Display Lights With colour coded LED indication of measurement and moisture state Green LED represents a safe, air-dry state. Yellow LED represents a borderline State. Red LED represents a damp state. Accuracy ±0.5%n or ±0.5% Measurement Range  7~30%  Operating conditions Temperature : 0 ℃ ~50 ℃ Humidity : below 90% RH Power Supply 4x1.5vAAA Um-4 Battery Size Main Unit: 140x70x30 mm Sensor Probe: 370x25x25mm Weight Main Unit: 130 g (Not including batteries) Sensor Probe: 290 g