Stainless Steel Serrated Flange Nuts are perfect if you ever need to loosen or remove items from your dock. Unlike standard nuts or lock nuts, serrated flange nuts go on tight and remain snug on the bolt until you loosen with a wrench or impact. They are perfect for use on boat dock accessories such as ladders, mooring cleats, or anywhere you use a bolt that you might have to remove later. Bolts made of ASTM F593 stainless are of higher quality alloy steel than A-2 stainless. With a higher corrosion resistance, these fasteners are the best use for coastal climates and are able to hold up to saltwater. The serrated flange nuts stay put until you remove them at the end of the season. The serrated flange nut fits 5/16-18″ bolts and are sold 12 flange nuts per package.