Product Description Item Number | N750052LNorth by Honeywell Mercury Vapor & Chlorine Respirator Cartridge Includes "End of Service Life Indicator" for Mercury, New Lower Profile design Cartridge for Mercury Vapor & Chlorine Includes "End-of-Service-Life" Indicator for Mercury 2 cartridges per pkg (1 pair) Color Code: Olive All North Cartridges are interchangeable for the North 5400, 5500, 7600 and 7700 Series Face-pieces.OSHA's Standard for respiratory protection, 29CFR 1910.134, requires Employers to implement a change schedule for all vapor and gas cartridges when there isn't an end-of-service life indicator on the cartridge. This schedule must be site specific and take into consideration work site humidity, worker breathing rate as well as contaminant concentrations.