Carpeted bunkboards provide proper center loading even in wind or side current conditions. Adjustable boat guides can be fine-tuned to work with your boat and your trailer. The pre-galvanized steel support posts mount horizontally on top of or below your trailer's frame rail. Just slide the posts into the boat guide supports and secure the posts so that the distance between the bunks correctly matches the width of your boat. The bunk boards then tilt to conform to the boat's hull. Guides will help to center your boat during loading and to hold the boat during transport. Sold in pairs Height of 21'' with adjustment out to 13"" from frame on each side Complete with mounting hardware to fit frames up to 3'' wide x 4-1/4'' high. Can be mounted on top of frame for extra height Made in the USA | C. E. Smith 5' Bunkboard Guide-Ons