The HI1270 is the replacement pH electrode for the previous model of the HI98103 Checker pH meter. Replacing the pH electrode is both quick and easy. Simply unscrew the old probe to be replaced and screw on the new one. The HI1270 is the replacement pH electrode for the HI98103 Checker pH meter prior to the meter's update. The HI1270 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.