Product Description The 3M Retainer 501 is a respiratory protection system component that 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. It is a well-made product that fits well. Raven Industrial Supply 413459
