Prong back ups are a safety clip meant to be clipped from a secondary collar (not the prong) to your leash. If the prong fails or becomes undone, it’s a safety device so your dog is not free from the leash.Mini – 6″ in total lengthStandard – 8″ in total lengthBrass, Nickel or Onyx (black) hardwaredisclaimer – always consult a professional when using a new training tool like a prong collar. These are best for medium to large size dogs as the prong backups may be too heavy for small dogs.