Zinc plated boat trailer replacement roller shaft. This item will work with a 12” roller that has a 5/8” inner diameter. This item has a 13.5” overall length and is 5/8” in diameter. If you are looking at this item, more than likely your previous roller shaft has completely rusted out or broken to the point where it is un-usable. This length is used on the 12" Boat trailer keel rollers. The most common way to secure this shaft on your bracket assembly is with two 5/8 inch Zinc Plated Boat Trailer Roller Shaft Pal Nuts. Having a roller shaft is great working conditions will help prevent your keel rollers from becoming damaged and failing. This 13 1/2" length keel roller shaft typically mounts inside the 12 inch Galvanized Keel Roller Bracket.