Check the listing for details. pH 4.01 Calibration Buffer Sachets (25 x 20 mL) from Hanna Instuments. Condition: New. Listed at 67.00 USD. Cleaning out the shop! This auction for 3 unopened boxes of 20 plus 5 more individual packets for a total of 65 sachets. HI70004P is a premium quality pH 4.01 calibration solution. Each sealed sachet holds just the right amount of pH buffer solution making every sachet as fresh as the day it was packaged! Highly portable, with a small footprint and a lightweight design.Color coded label for easy identification of pH 4 buffer value. HI70004P is a quality pH 4 calibration buffer produced in accordance with ISO 3696/BS3978 standards using high purity salts, deionized water, certified weight-checked balances, and Class A glassware in a temperature controlled environment monitored with certified thermometers. Reported values are accurate to +/- 0.01 pH @ 25°C and are traceable to NIST Standard Reference Materials (SRMs). Convenience of individual packaging Ideal for users that do not calibrate frequentlyIdeal for field use due to portabilityEvery pH buffer sachet is as fresh as the day it was packagedLight block packaging prevents oxidation from UV light that could alter the buffer value Each sachet marked with lot number and expiration date. Hanna pH buffers are specially formulated to have an expiration of 5 years from manufacture for an unopened sachet. Color coded label for easy pH buffer value identification Easy to identify different buffer valuesSolution does not contain any dyes that may stain the reference cell of a pH electrode Perfect for use with testers and portable meters!