This is for one package of ten (10) quality marine grade stainless steel (AISI 316) 1/2"-12 Whitworth Hex Head Nuts. These are a British Whitworth thread, and require a British Whitworth bolt with pitch of 12. This nut is passivated for a better finish and also makes the nut more resistant to corrosion. Not to be used for overhead lifting. This nut meets the American Society of Mechanical Engineers ASME B18.2.2 and the American Society for Testing and Materials ASTM F594 specifications. It has six flat sides that a wrench can grip to turn from the side, enabling use for when there is no space above the nut. Nuts are internally threaded fasteners that are used with bolts and threaded rods and studs to connect components. AISI 316 stainless is a premium grade of stainless and is considered by many to be best in class. 316 stainless is corrosion resistant and very durable even in the harshest of conditions.