Allen Hex Drive: 5/32 inch or 4mm hex wrench size; Quantity: 25-pack Thread Size: 1/4-20; Thread Type: 20 TPI Coarse Thread (UNC); Thread Style: Right Hand; Thread Coverage: Full Thread Material: Made of 304 Stainless Steel with black coating outside which is superior to regular stainless steel fasterners, provides better strength and corrosion resistance in bad environments like high temperature, cold weather and high humidity areas without the need for time consuming and costly maintenance Design feature & Applications: Design with internal socket drive for installing in areas with limited side clearance; They are known for their efficient application performance and endurance widely used in a variety of industries such as home, construction, manufacturing, engineering, assembling, aircraft for both professionals and amateurs Diameter of the Head: 0.437 inch; Thread Length: 1.25 inch 1/4-20 x 1-1/4" Button Head Socket Cap Bolts Screws, 304 Stainless Steel 18-8, Allen Hex Drive, Black Oxide Coated Finish, Fully Machine Thread, Pack of 25