I put 4 stars for product reliability, for some I was looking for a PH meter for my aquarium and so far I used the strips but in my opinion not quite inaccurate and unreliable measures. Upon delivery no product problem in a bubble-bubble envelope and PH meter is well protected in a plastic box there are also the small screwdriver for calibration and the method of application and two doses PH 6.86 PH 4.0 and for calibrating the pH meter. No need to put the batteries, the PH tester is near to the front we must nevertheless proceed to the calibration of the pH meter used as indicated in the instructions just carefully follow the procedure for purpose in a reliable product. One star less for instruction in English but fortunately Google translation is there and we can get along and are also found on youtube a video for calibration. In short I found the reliable measurement confirmed by a chemist friend and I recommend this product for its low price and also reliability. As regards the solution undercut are found on the web or in sachets or 250ml.
