Black 8" Perm (Stainless Steel Pin Tail) (Course Teeth) and Black 8 1/2" Perm (Stainless Steel Pin Tail) (Extra Fine Teeth). Manufactured exclusively from Nitrile Rubber. Nitrile Rubber will not absorb sterilizing solutions, perms, conditioners, shampoos, oils, water, etc., and can be wet or dry sterilized. Teeth are perfectly "matched" to eliminate drag, split ends, or scratching.