GAIN EXPRESS PH Meter 360° Flexible Display Angle, 0.00~14.00pH Portable Pocket Size Water Quality Tester Twist & Turnable Monitor Kit Set for Household Drinking Water, Hydroponics Aquariums Pools

these meters are junk. do not waste you money.....i had one that worked great for a couple days, then went on the fritz, tap water testing at 8 went to 5.4. re calibrated and still said 5.4 for tap water. it then quit working totally with no readout. tried new batteries...NOPE.. I figured it was just bad so got another one...exactly the same unit. worked a few times, then tap water at 8.79, 8.80 and then 5.9 and bouncing all over....these are one week use meters if you are lucky and they are very unreliable. I kept it clean and put the cap on and stored in the protective case it came in. this meter will kill hydro plants and aquatic animals for you due to its inaccuracy. if that is your application, please steer clear. This company makes a nice multi-meter, but this product is a bust. ZERO STARS I gave 1 cuz i had to in order to submit this review. I usually never give reviews as i see it a waste of time, but i felt obligated to the community to pass this on. scroll on and find another meter. i went bluelab and am awaiting its arrival.