These smooth-rolling guides assist in centering your boat on a trailer. Ideal for retrieving your boat on shallow ramps where the trailer is not far in the water, when you are alone, or when a crosswind or current is pushing the boat and making it harder to maneuver. Pre-galvanized steel uprights lean outward 15° to cradle the boat. Guide-ons are 21" tall above the frame with 9" roller caps at the top and bottom. Mounting hardware is included for frames up to 3"W x 4-1/4"H. Brackets allow up to 13° of adjustment from each side of the frame. Uprights with rollers come fully assembled and ready for installation.