Trailer Hitch "Shin" Protector. Everyone has hit their shin on a trailer hitch * at one time or another. The "Hitch Doktor" protects you from hurting you shin * when you hit the trailer hitch. ? Made of long lasting durable Vinyl Coated Foam Rubber. ? UV Resistant ? Slips over most Trailer Hitch Ball and Nut. ? No need to remove it. ? Nothing to keep track of when pulling a trailer.