Fulton Boat Roller Guide-Ons help visually guide your boat onto your trailer. These guide-ons feature steel construction with non-marring, cushioned rollers. High-strength, super-grip mounting brackets attach firmly above and below the trailer frame. Easy bolt-on mounting fits trailer frames up to 3" x 5" high. 15" total side adjustment to fit most hull designs. 20" high. Mounting hardware included. Sold in pairs.