The Attwood Spool/Keel Roller 11317-1 aids the easy loading or launching of your boat. It's outside diameter is 5 inches. Its polymer construction makes it durable, long lasting and impervious to sunlight/UV damage, chemicals or fuels. Attwood Corporation has been an award-winning leader in engineering, testing, and manufacturing the highest quality marine products for over 100 years. We deliver safe and reliable lighting, fuel systems, water systems, seating & pedestals, swim ladders, custom upholstery, and general marine accessories that are easy to install and meet regulatory compliance.