Smith Trailer Post Guide-Ons give a clear visual marker to indicate when you're backing, loading, or unloading your boat trailer so you avoid costly damage. Unlike other guide-ons that fall apart or break with minimal impact, Smith guide-ons include 16-gauge steel uprights and are pre-galvanized for corrosion resistance to ensure use season after season. 2-3/8" PVC posts are 40"H. Will fit trailer frame 3"W x 4-1/4"H. Pre-galvanized 16-gauge steel uprights Designed for corrosion resistance | Smith 40" Trailer Post Guide-Ons, Pair