Designed for continuous monitoring of pH, TDS and temperature, the HI 981504 is simple to install and can be placed above the sample to be tested. pH, TDS and temperature measurements are simultaneously displayed on three backlit LCDs which can be easily viewed at a distance - even in low light. The HI 1286 gel-filled pH electrode is provided with a waterproof sheath to protect the BNC connector. The unique design of the electrode provides longer life in aggressive solutions. The HI 7634 TDS probe is easy to clean and requires little maintenance. Measurements are accurate and the meter can be calibrated at one or two points for pH and at a single point for TDS. Temperature range is factory calibrated.