PACK: 50 M8 serrated flange nuts in 304 stainless steel according to the. SIMPLE AND EFFECTIVE: Thanks to its wide base, this nut, also called a collar nut / flange, offers a larger bearing surface than a standard hexagonal nut. It is an essential fastening element because it does not require a washer, it offers greater resistance to loosening than a standard nut while ensuring simple, quick and efficient assembly. SAFETY AND LOCKING: The notches on the base allow the nut to be locked so that it does not loosen. This durable, high-quality nut is easily installed with a 13mm open-end wrench on 8mm diameter screws or threaded rods. WON'T RUST: 304 stainless steel. Unlike zinc-plated or galvanized steel, this stainless steel nut resists corrosion and will not rust. It is therefore suitable for indoor and outdoor use, even in humid environments (excluding seawater).