Ideal for jon boats, bass boats and personal watercraft. The guide posts are made of 1-1/2\" square, 16-gauge steel tubing and galvanized for long life. Guide covers are made from high impact non-marking molded PVC. Low Rider Guide On\'s give you the extra advantage of high strength and great looks for your trailer. Mounts to trailer cross members 2\" x 2\", 2\" x 3\" and 2\" x 4\" frames. All mounting hardware included.