1Used for measuring the amount of redox potential (ORP) level. 2Transparent LCD with backlight, convenient and simple reading. 3Suitable for water source, aquarium, hydroponics, spa, swimming pool and other water systems. 4Compact and portable pen design, small size, easy to carry. 5Easy to use, and it can provide instant display of results.ORP meters is the ideal tool for professional testing of water levels. Suitable for water source, aquarium, hydroponics, spa, swimming pool and other water systems. Transparent LCD with backlight, convenient and simple reading.Features:1. Used for measuring the amount of redox potential (ORP) level.2. Transparent LCD with backlight, convenient and simple reading.3. Suitable for water source, aquarium, hydroponics, spa, swimming pool and other water systems.4. Compact and portable pen design, small size, easy to carry.5. Easy to use, and it can provide instant display of results.Specification:Range: -1999mV - 1999mVResolution: 1mVAccuracy: 5mVWorking temperature: 0C-50C (32F-122F)Battery: 2 * 3V (CR1632) button battery (not included)Package list:1 * Installation tool set1 * Instructions