3M™ Retainer 501 is designed for use with the 3M™ 07046 Organic Vapour Cartridges and the 3M™ Organic Vapour/Acid Gas Cartridges 07047 to attach the 07196 P95 filters where there is a need for particulate protection such as in a paint spray application. This retainer is reusable and should be replaced when it becomes worn or damaged.