Blue fiber screen filter for added protection.  Traps dirt in filter screen rather than allowing it to build up on the top screen of the dirt canister.  Can be washed and reused 3-4 times. Great for specialty debris such as hair, powder, etc. For VacuMaid units with DC1240 including P350P, S3600, S3600T.   14" Diameter x .5" to .75" thickness.