Come and Check Our Branding Solutions.After pressing the button, the belt will be fixed. After sliding the push button to the back, the belt will be locked. Slide the push button forward and your dog will be able to run back and forth easily. This button ensures the capability to adjust the length of the leash as you need and make the leash to keep a constant length , which make sure the safety of your dogs and yourself. Two sizes are available. It's suitable for small and medium-sized pets. Pls check inventory and detailed info before placing your orders.