【20 Pcs 5/16-18 x 1-1/2" Hex Socket Button Head Cap Screws 1 Pcs Hex Key Come In a Plastic Storage Box】 Contains 20 Pcs 5/16-18 x 1-1/2" hex socket button head cap screws --Meets/exceeds: ANSI/ASME B18.3BT --Thread size ( diameter ): 0.312"/7.93mm --TPI: 18 teeth per inch --Thread length: 1-1/2" ( 1.500"/38.10mm ), total length ( includes head ) 1.659"/42.14mm --Screw head style: button head, head diameter: 0.537"/13.64mm, head height 0.159"/4.04mm --Screw drive style: hex socket drive, also known as internal hex drive, hex size: 3/16" --Made of alloy steel 10B21, black oxide finish, high strength and anti-rust --Strength grade of screws : 10.9 Grade, hardness: HRC 32-39, tensile strength: 1040 N/mm2 Contains 1 Pcs hex key to drive these screws conveniently and easily --Hex size: 3/16" --Made of chrome-vanadium steel, nickel plated, higher strength, anti-rust Easy to store: 20 Pcs 5/16-18 x 1-1/2" hex socket button head cap screws and 1 Pcs hex key come in a plastic storage box, organized conveniently and easily [ Package Contains ] 5/16-18 x 1-1/2"-----20 Pcs Hex Key------1 Pcs [ About Hex Socket Drive ] Hex Socket Drive, also known as Internal hex drive, have a hexagonal hole in the center that requires an Allen key, also known as a hex key or Allen wrench [ About Button Head ] Button head is similar to standard pan head screws but have a curved top