Features: Weight: 53 g pH range: 0.00 - 14.00 pH. Resolution: 0.1 pH Accuracy: ±0.1 pH Operating temperature: 0 - 50 C (32 - 122 F) This digital pen acid and alkali instrument is an ideal instrument for aquarium, fishery, swimming pools, school laboratories, food and beverage industries. Please use buffer calibration before use.