Chain Collar.  Dede was given advice from a Veterinarian that between these and prong collars, these do more trachea damage.  She recommends these for dogs whom chew their collars off, for those that you need to be sure don't get out of a collar, and as a back up collar when using a prong collar clipping both together in case of escape.  Pieces are removable to fit the collar closely if needed.  All Sales Final