A perfect solution for your escape artists, martingale adventure collars offer a more comfortable solution over traditional choke/pinch collars. Simply attach your leash to the d-ring and the collar will automatically tighten as your dog pulls on the leash, preventing them from being able to slip out of the collar during your walks together. Reflective stitching. Black neoprene comfort padding. Three adjustable sizes. Metal d-ring (for leashes). Available Sizes Small 5/8" nylon - adjusts to fit 10" to 14" Medium 3/4" nylon - adjusts to fit 14" to 20" Large 1" nylon - adjusts to fit 18" to 26"