CURT snap hooks are a highly secure way to connect your safety chains from your trailer to your tow vehicle. They feature a spring-loaded safety latch that turns the hook into a closed loop. Similar to a quick link, the safety latch allows for a safety chain connection that won Inch come loose from vehicle vibrations or jarring on uneven terrain. Snap hooks also feature a strong steel construction and come with a zinc-plated finish to outlast the elements. This particular snap hook has a 9/16 Inch diameter and offers a gross trailer weight capacity of 5,000 Pounds. Remember, when attaching safety chains, the chains should be cross underneath the trailer coupler, and each hook and chain must be rated to meet or exceed the gross weight of the trailer.