Half Nut Hex (Lock Nut) UNF 9/16 inch in Zinc Plated Steel - ANSI B18.2.2 SAE J995
Nut conforming to ASME B18.2.2. Also known as a half nut, thin nut, or jam nut. Typically fitted with a spanner or ratchet with socket, often used in pairs in a nut locking arrangement. A popular nut type, and used for decades on all types of assembly throughout the world.