3M Filter Retainer 501 is used to hold 3M Particulate Filters 5N11 and 5P71/07194(AAD) in place on top of 3M Respirators 5000 Series and 3M Cartridges 6000 Series. 20 per dispenser. The 3M products on this page must be used in accordance with OSHA regulations, and the user instructions, warnings and limitations accompanying each product.