**DISCLAIMER** Command Slip Collars are training aids only and are to be used under supervision at all times. These collars are alternatives to traditional choke chains - strong enough to provide correction, yet soft enough to provide comfort. Sizing: 3/8″ x 16″, 18″, 20″, 22″, 24″ and 26″ Sizes are measured from the inside of one ring to the other ring. We recommend sizing up at least 2 sizes from your dog's neck measurement to allow the collar to fit over largest portion of your dog's head.