304 stainless steel has high strength and hardness grades, and is corrosion-resistant in mild environments Flange nuts are used to distribute the pressure of the nut onto the fixed parts, reducing the chance of damage to the parts and making them less likely to loosen due to uneven fastening surfaces. Due to serrations, they cannot be used with washers or on surfaces that cannot be scratched. Sawteeth help prevent nut vibration and increase the clamping force of the nut.