The HI1131P is a glass body, refillable, double junction pH electrode with a BNC and pin connector. The pin connector is used to enable the CAL Check function of the HI2221, HI2222, and HI2223 benchtop meters. This electrode has a single ceramic junction in the outer reference cell and the spherical pH sensing portion is made with high temperature glass. This design consideration is ideal for laboratory samples, liquid samples, and high temperature samples, as well as general purpose use.