C. E. Smith Shipshape 27670 Trailer pontoon post guide-on, 1 1/2" square 16-gauge pre-galvanized steel uprights, 2 3/8" diameter white PVC posts, 22" high, fits frames up to 3" wide x 4 1/4" high. Installation instructions and mounting hardware included. When loading your pontoon boat onto your trailer, it is much easier with post guide-ons. These guide-ons mount on top of rear cross member and fit in between the pontoons to center your boat on the trailer. Sold in pairs.