The Extech RH300-CAL is a humidity calibration kit contains two reference standards: one for 33% relative humidity and one for 75% relative humidity. These standards are used to verify the accuracy of humidity meters, specifically the Extech RH350 Advance SuperHeat Digital Datalogging Psychrometer. The 75% reference uses Sodium Chloride (NaCl), while the 33% reference uses Magnesium Chloride (MgCl). Bottles have small opening designed to snuggly fit the remote sensor probe.

The Extech RH300-CAL is a humidity calibration kit containing two reference standards: one for 33% relative humidity and one for 75% relative humidity. These standards are used to verify the accuracy of humidity meters, specifically the Extech 445815. The 75% reference uses Sodium Chloride (NaCl), while the 33% reference uses Magnesium Chloride (MgCl)