Oakton Waterproof pHTestr 30 is a top grade pH reader. This unit contains dual display of highly accurate (.01) pH and temperature (Celcius) readings. Contains a three point push-button calibration system that allows you to read a pH range of 1.0 to 15.0. The double junction electrode setup of this tester is also ideal for dirty water, heavy sulfides and organics. The sensor can also be replaced, allowing you to save money by not replace the whole unit. The increased reference gel volume also offers a significantly longer electrode life. Get the IP67 certifiable pH tester to increase the quality of your system.