For 2" square gate frame and 4" square post Includes heavy duty ABS cover to protect rollers and bearings in all weather conditions Includes strong magnets to help position the roller when mounting New, improved heavy design Extreme weather resistance Includes heavy duty covers Quick mount magnetic base Galvanized metal components for long lasting performance. Machined 7" diameter nylon roller provides smooth operation. Also feature 1-1/8" axles and heavy duty bearings. Heavy duty ABS covers can be mounted on top or bottom.