Review on Apera Instruments SX620 pH Pen Tester Kit: Accurate Results with 0.01 pH Accuracy, 3-Point Auto Calibration, and ATC by Elvis Bragg

Worth the Money This is definitely a lot more than the cheaper models you can find on ebay (only $10!). It has 1 point calibration which was the main reason I bought it. Calibration is required at least every other use, but it is very quick and easy to do. I've found that the readings tend to vary by 0.1-0.2 pH, especially with liquids that generally "foam" (I use this mostly for canned fruit). I usually take 5 or 6 measurements and choose the one that works best. These are delicate instruments and should not be handled roughly. That means it's a pretty solid little unit. It fits easily in a short test tube, but not in a longer one. The case is excellent and has a small supply of necessary liquids. Everything says I'm in love with this device. I think it compares to the more expensive Hanna and Oakton gauges I've had in the past. The accuracy seems to be on par with any other gauge under $100.