|b||minimum thread length|
|k max.||maximum head height|
|t min.||minimum recess depth|
|Standard||ASME B18.3, ASTM F837-13e1(CW)|
UNF Socket Head Cap Screws ASME B18. 3 . Also known as an Allen screw or Allen bolt, or simply a cap screw, socket head cap screws are a more modern alternative standard machine fastener to the standard hexagon headed bolt or setscrew, as found on much modern machinery.