Heavy duty 8inch keel roller for boat trailer, self centering, 0.67in aperture1、Self Centering Design: The 8 inch self centering keel roller bow stop is engineered with built in grooves that help center your boat as you load it onto your trailer, ensuring a smooth and accurate positioning process. 2、Non Marring: Made from heavy duty PU material, offering excellent resistance to corrosion, maintains its strength in both saltwater and freshwater environments without leaving scuffs, scratches, or marks on your boat's hull. 3、Superior Strength and Longevity: This roller bow stop has strong and longer lifespan, robust construction ensures it won't wear out quickly, providing consistent support for your boat's keel over time. 4、Keel Support and Shock Absorption: The bow stop guides the keel to the center of your trailer, supports it as it rests, reducing the strain on your boat, absorbs road shock while being towed, minimizing the impact on your boat. 5、Efficient Loading and Unloading: You can easily push your boat onto the trailer, speeding up the loading process, well designed roller operates smoothly, enhancing work efficiency.