Specifications: Thread Diameter :6 mm/0.24inch Head Diameter: 10 mm/0.4inch Head Height: 3.3 mm/0.13inch Screw Length: 40 mm/1.57inch Allen Hex Drive: 4 mm/0.16inch Material: High Quality Stainless Steel 18-8 (304) Weight: 165g Package Included: 20 x M6 40mm Button Head Socket Screws About Button Head Socket Cap Screws Button head socket cap screws are precision threaded threaded fasteners with an internal socket drive (also called allen hex drive) for installing in areas with limited side clearance. The internal hex drive requires an allen wrench. They are known for their effecient application performance and endurance widely used in a variety of industries such as construction, manufacturing, engineering, assembling, aircraft and so on and serves a wide range of use for professionals, amateurs, landlords, repairmen and DIYers. These screws are available with a variety of head shapes, which determine how the screw interacts with the mating surface, and drive styles, which determine the type of tool required to install the screw.