Extech PH103 Tripak Buffer Pouches 4, 7 and 10 pH with Rinse Solution Kit Pre-made convenient calibration solutions for pH meters Easy to use, already made fresh pH buffers for calibration 6ea. of 4, 7, 10 pH plus 2 Rinsing solutions Helpful table printed on the pouch shows what the pH value should be vs. the temperature of the buffer solution measured Rinsing solution for cleaning the electrode before taking the next measurement to prevent contamination