Gain Express Pen Type EC Hydroponics Nutrient Meter Water Quality Tester Aquarium Spa Laboratory Automatic Temperature Compensation Measuring Range 0~19.99ms/cm Wide range of applications in water quality testing Equipped with Electrode for extreme durability, excellent conductivity & accuracy Easy push power button and calibration with the mini-screw driver CE Approval and ideal for the most demanding of users Compact and light weight for mobility