The filter P941 is a particle filter that protects against dusts. It is a P3 R type and protects against toxic substances such as particles and microorganisms. The special Portwest bayonet system ensures a safer connection between the mask and the filter while the twin filters offer improved comfort and balance. This filter is compatible with the P500 Full Face masks and the P420, P430, P421, P431 Half Masks. Portwest P3 Particle Filter Bayonet Connection, Brown