CE Smith 60″ Post Guide-Ons with I-Beam Mounting KitThese 60″ beams help you keep track of your trailer when underwater when loading your boat. Specifically designed for I-beam trailers and boat lifts. An innovative two-piece mounting clamps work above or below the I-beam. Works with almost any I-beam width and the brackets fit onto any height.Product Features:Installation Instructions IncludedAdjusts out to 19″ on each side1-1/2 square, 16 gauge pre-galvanized steel uprights2-3/8″ Diameter white PVC postsMounting Hardware includedPre-Galvanized SteelSold in PairsPre-galvanized steel parts are stamped from a sheet of steel after it has already been galvanized. The galvanized coating is very thin (0.45 oz. on each side).