This anti-gas and anti-particles filter protects from organic and inorganic acid gases and vapours sulphur dioxide ammonia and its derivatives. Classified as a class 1 filter for gases and class 3 for particles it protects against harmful substances solvents toxic particles and micro-organisms. The special Portwest bayonet system ensures a safer connection between the mask and the filter. This filter is compatible with half masks P420 P430 and Full Face masks model P500.