The manual retractable truck bed covers are available in either the polycarbonate series or the premium aluminum series. The manual retractable truck bed covers effortlessly glide along the rails by the sealed ball-bearing roller system with a convenient handle that eliminates the need for pull straps, Velcro, snaps or springs. The manual retractable truck bed covers are key lockable in any position along the rail providing unlimited flexibility in your hauling capacity.