Durable pocket-sized pH meter is supplied with a rugged silicon chip ISFET pH sensor for fast, stable readings on an LCD. Waterproof meter measures samples as small as a single drop and features a replaceable reference electrode; automatic buffer recognition of pH 4 and 10; up to three point calibration of pH 4, 7, and 10; automatic temperature compensation; 10-hour advance low battery warning; and automatic power-off.