The essential Boat Guide On Kit that allows you to line your boat up on your trailer, even on the windiest of days, or in difficult ramp conditions. All hardware is hot dip galvanized for corrosion protection Fits frames up to 4-1/4" in size The bunk boards mount 19" above your trailer frame and have 11" of side movement on each side Sold in pairs with all hardware included. Creates a lightly padded guide incase your boat just doesn&';t want to line up right