Wide Application: These boat trailer guides are suitable for ski boat, fishing boat, or sailboat trailers, and they make loading the boat so much easier. With PVC Posts: The two PVC pipes with end caps can be fixed firmly onto the brackets, and they will prevent the boat from being scratched. Add the frames effortlessly and keep your boat protected. Solid Construction: The brackets are made of 0.12" thick steel and are powder-coated, so they work great against saltwater and do not easily rust or bend. Flexible Installation: Our trailer guide-ons can be mounted on top of the frame or below it, and the U-bolts fit both large frames and smaller frames. Adjustable Width: The width of these trailer guides can be easily adjusted, extending to 15 inches at most. They are compatible with trailer frames less than 3" wide and 4-1/4" tall.