Product review (1 stars): Buy the General Hydroponics test kit instead. It may ...
Buy the General Hydroponics test kit instead. It may not give as accurate a reading but it works when you need it.

I used all the buffer solutions just to get this thing calibrated. Within a week it needed to be re-calibrated (I even spent $$ on liquid to properly store the meter). Between the buffer packets, PITA calibrating, distilled water and headache it's not worth its weight.