Hanna PH4 Calibration
Hanna's Buffer solutions are made from established formulas and are standardized with a pH meter that is calibrated to NBS/NIST primary standard buffer solutions. Now the pH 4 buffers carry lot #, expiry date as well as pH/C chart on every bottle. HI 7004L/C and HI 8004L/C are also supplied with an analysis certificate. 16oz. Bottle.