Whether you're carrying one boat or four, the Yakima Kayak Stackers give you an efficient, secure way to do it. Arrow-shaped tops ensure your straps or ropes are held tight. Ideal for any plastic kayaks. (Be sure to check the cargo load limit of your car first!) Non-scratch coated steel is heavy duty but won't scratch your boats. Arrow tops keep straps and rope from sliding off. Mounts to square or round crossbars (or to factory roof racks with the addition of Yakima Horizontal MightyMounts, not included). Kayak Stackers work great for most plastic, roto-molded boats. If in doubt, check with the maker of the kayak for specific boat transport on edge advisability. Sold in pairs, includes two 16' Yakima padded Heavy Duty Straps.