Apera Instruments PH60F-E Probe is the replacement probe for Apera PH60 Series Premium pocket pH testers, including PH60F, PH60 and PH60S. It is also compatible with PC60. This probe features a flat glass membrane sensor with a built-in thermister, triple-junction structure, and maintenance-free gel KCl electrolyte, made for surface pH testing such as skin, fabrics, paper, leather, carpet, and micro-volume solution samples. It also works well for regular water solution testing.