This is a Single Length of Safety chain with dual securing hooks for mounting to the tongue of your boat trailer or utility trailer. Trailers are required to have these for added safety while towing. This listing incorporates both chains into one single length with two hooks. 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 48 inch long, 8/0 link diameter, Grade 30 Safety Chain with dual hooks. This chain has a 7,000 lb Breaking force. The S hooks are 17/32 inch diameter.