EzyDog Zero Shock Coupler Red Dog Lead Attachment 24"Both ends of the coupler include Zero Shock technology. Zero Shock represents the advanced shock absorbing component in the center of the extension that cushions and eases the pressure for both you and your dog. Zero Shock Technology to absorb any sudden jolts, made from our proprietary Soft Touch Webbing. Traffic Control Handle located near end of coupler for close control of dog in built up areas.