Ensure excellent organic-vapor filtration performance when you choose MSA NIOSH-Certified replacement cartridges. Threaded base simplifies filter changes while ensuring secure attachment. Designed for Comfo? Classic, Ultra-Twin?, Ultra Elite? Twin-Cartridge and Duo-Twin? Respirators. Filter Type: Gas/Vapor; Filtration For: Organic Vapors; Rating: GMA; For Use With: MSA Comfo? Classic, Ultra-Twin?, Ultra Elite? Twin-Cartridge, Duo-Twin? Respirators.