The Combo Waterproof Tester takes highly accurate readings of temperature, pH, EC and TDS. The unit is protected by a strong plastic waterproof casing, and comes equipped with a replaceable pH electrode, salt-resistant stainless steel EC/TDS and temperature probes, electrode replacement tools to make maintenance simple, batteries and a self-check feature. A low-battery alert ensures proper functioning and the unit also automatically notifies users when to take and when to freeze the reading for accurate measurements; this tester also features automatic temperature compensation. 2lb