Usage With the Redox Meter type, the oxidox potential (ORP) is measured. Backlit LCD display The water quality tester has a clear LCD display with backlight, convenient and easy to read. Wide ApplicationThe portable ORP tester is very suitable for water sources, aquariums, hydroponics, bathrooms, swimming pools and other systems hydraulics. Pool Water Tester Small and PortableThe pH water tester has a compact and portable pen design, it is small and easy to carry. Easy to UseThe digital water quality tester is easy to use and provides an instant display of results. ORP meters are the ideal tool for professional monitoring of water levels. water. Suitable for water sources, aquariums, hydroponics, bathrooms, swimming pools and other hydraulic systems. Transparent LCD display with backlight, convenient and easy to read. Specifications: Range: -1999 mV - 1999 mV Resolution: 1 mV Accuracy: 5 mV. Operating temperature: 0C to 50C. Battery: 2 x 3 V button cells (CR1632) (not included).