The 3M Filter Retainer 501, Respiratory Protection System. Coming in a translucent white color, this product is used in various applications, including, assembly and mechanical, cleaning, composite finishing, final finish, paint preparation, painting, welding. The 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).