The Oakton WD-35634-12 EcoTestr Salt1 tester is an economical, simple-to-use pocket testers quickly measure conductivity, TDS, or salinity levels accurately while simultaneously displaying the temperature. A large dual-line display makes viewing measurements easy and features indicators for measurement stability, calibration, and battery life.|Additional features of the WD-35634-12 include a long-lasting, durable electrode with polymer reference electrolyte, auto recognition of calibration standards, and self-diagnostics. The IP67-rated housing features an easy-to-grip design and floats if accidentally dropped in water when sensor cap is on. The testers, powered by 4 AAA batteries, can operate up to 400 hours continuously. The unit will auto power-off after 8 minutes of non-use to conserve power.