This is a Single Length of Safety chain with clasping securing hook for mounting to the tongue of your boat trailer or utility trailer. Trailers are required to have these for added safety while towing. You would have two of them, one on either side of the tongue coupler, for attaching to the hitch loops on your tow vehicle. Depending upon your trailers coupler set up, these are either bolted or welded to your trailer. On Boat Trailers, these would be bolted directly to the coupler or tongue of your trailer. It can not be stressed enough how important it is to have safety chains on your trailer. Having properly functioning safety chains will prevent a bad situation from turning into a disastrous situation. This listing is for a Single Length of 31 inch long, 3/8" link diameter, Grade 43 Safety Chain with a Single Clasping Hook. This chain has a 15,000 lb Breaking force. This safety chain is also commonly seen on gooseneck trailers.