The Extech PH115 ExStik Replacement Refillable pH Electrode Module For Extech PH100/PH110 Meter provides an economical way to refill your electrode and eliminates the problem of limited electrode shelf life, contamination, and usage life. The PH115 is easy to clean, and features a rugged flat surface Refillable pH electrode, an ATC via built-in Pt-100Ohm sensor, and a protective connector cap. The PH115 is interchangeable with ExStik® Chlorine or ORP meters.