The waterproof ExStik® PH100 pH meter by Extech is an accurate, rugged and reusable stick pH meter with some unique data storage features that make it exceptionally easy to use and considerably enhance its usability. The flat surface electrode allows you to measure pH in liquids, semi-solids and solids and limits electrode breakage and clogged junctions. The Renew indicator tells you when it's time to replace your electrode. The CAL alert ensures consistently accurate readings by telling you when you need to recalibrate. A Memory feature records and recalls 15 sequentially tagged readings, so you will know how your readings have changed over time. The LCD readout displays pH, temperature and an analog bargraph that shows trends in acidity or alkalinity and indicates when the reading is stable. 1, 2 or 3 point calibration automatically recognizes buffer solutions. Other features include automatic temperature compensation, auto power off, low battery indicator and data hold. The PH100 comes with a protective sensor cap, sample cup, four 3V CR2032 button batteries and a 48 in. (1.2 m) neck strap. For more convenience, purchase the EX006 weighted base, which holds both the sample cup and ExStik® meter.