1960s / 1970s vintage mouth guard number MKP431. Got a box of these when Dixie International went out of business. I believe these attached to open face helmets. Please know that it appears the snap has a bolt and not with it so you have to drill the helmet in order to attach this mouthguard. If you already have snaps in the appropriate place on your helmet then you won't need to use the snaps provided.  Please note these are for VINTAGE helmets only.  This will not work on newer helmets.