Hanna Calibration Solution pH 4 & 7 (5 x 20ml of each) – Hi-7740

A box of 10 sachets. 5 of pH 4.01 Hi-77400P buffer solution and 5 of pH 7.01 buffer solution. Each sachet contains 20ml of solution and can be used to calibrate any of our pocket meter range, or any pH meter with a conventional pH electrode.