Portwest ABEK2P3 Combination Filter Universal Thread (Pack of 4)This anti gas and anti particles filter is equipped with a standard DIN threaded connection conforming to EN 148 1 and can be used on full face masks with the same connection. It protects from organic and inorganic acid gases and vapours, sulphur dioxide, ammonia and its derivatives. Classified as a class 2 filter for gases and class 3 for particles, it can be used to protect against harmful substances, solvents, toxic particles and micro organisms.