C.E. Smith Safety Chain Set, Class IV [16681A]Safety Chain Set (Pair) Class IV Product Description Zinc plated, proof coil chain features strong, heat treated S hooks to keep your trailer from separating from the tow vehicle if the coupler becomes unhitched. Remember to attach the open end of the hook up through the hole, not down, to prevent it from bouncing out. 24"L. Sold in pairs. 7600lb Capacity, 8 0 chain.