HI7007/1G is a premium quality pH 7.01 calibration solution that has been dyed green for easy buffer identification. Hanna calibration buffers have the lot number and expiration date clearly marked on the label and are air tight with a tamper-proof seal to ensure the quality of the solution. Hanna’s line of calibration buffers have been specially formulated to have an expiration of 5 years from the date of manufacture for an unopened bottle.