The Fulton Boat Trailer Guide Poles visually guide your boat onto your trailer for boat loading and launching. Boat trailer post guides are compatible with trailer frames up to 3-inches x 5-inches. Boat trailer guides poles can be adjusted up to 16-inches on each side to ensure a custom fit to any boat hull design. The non-marring, marine grade PVC tubing helps prevent damage and marks to your boat. Easy to clamp on, no drill installation features high strength, super gripper, bolt-on mounting brackets that attach firmly above or below the trailer frame to maximize mounting flexibility.