The HI1271 is the spare pH electrode for the HI98100, HI98103, and HI98115 Checker pH meters. Replacing the pH electrode is both quick and easy. Simply unscrew the old probe to be replaced and screw on the new one. The HI1271 is the replacement pH electrode for the HI98100, HI98103, and HI98115 Checker pH meters. The HI1271 is a single junction pH electrode that has a slim 8 mm polypropylene body that easily fits into test tube and other small sized vessels.