The Tris-Compatible Flat pH Sensor (FPH-BTA) is made of an electrode connected to an Electrode Amplifier (EA-BTA). These special Electrode Amplifiers have been burned so that they default to Page 1 and therefore auto-ID as pH instead of mV. If a unit reads mV, simply go into Calibration Storage in Logger Pro or LabQuest and point it to Page 1 instead of Page 0.