This is a replacement inhalation valve designed for 3M Half Facepiece Respirators 7501, 7502, and 7503.The 3M Inhalation Valve 7582, Respiratory Protection Replacement Part, works with 3M Half Facepieces 7501, 7502, and 7503 (all sold separately). This replacement part can extend the service life of respiratory protection equipment and potentially result in cost savings.