The 3M™ Filter retainer 501, respiratory protection system component holds 3M™ particulate filters 5N11 and 5P71/07194 (AAD) in place on top of 3M™ respirators 5000 series, 3M™ cartridges 6000 series and 3M™ filter adapter 603 (all respirators, filters, cartridges, and adapters sold separately).