CE Smith 16661A Safety Chains- Class II (Pair)Proof coil trailer coupler safety chains feature strong, heat treated S hooks to keep your trailer from separating from the tow vehicle if the coupler becomes unhitched. Zinc plated Integrated security spring clip prevents accidental un hooking Class II 24" long 3500 lb capacity 5 0 chain size Sold in pairs **Remember to attach the open end of the hook up through the hole, not down, to prevent it from bouncing out.