This is Kurgo's strongest dog tether system, featuring a carabiner used by arborists. It has been tested to support 20 KkN or 4,500 pounds of force. The swivel action prevents your pup from twisting or getting caught up in the tether. The locking carabiner prevents those sneaky escape artists dogs from getting out of their car restraint. Designed to restrain large dogs who never sit still!