Allen Cap SHCS
Allen Cap SHCS
Socket caps have a small cylindrical head with tall vertical sides. Allen (hex socket) drive is a six-sided recess [Internal Hex Socket] for use with an Allen wrench (hex key). This design is the workhorse of the machine building industry. 
The most important reasons for the increasing use of socket head cap screws in industry are safety, reliability and economy. All three reasons are directly traceable to the superior performance of socket screws vs. other fasteners, and that is due to their superior strength and advanced design. Available in full thread and half thread.
Standards: DIN 912, ISO 4762, Low Head – DIN 7984
Materials: Alloy Steel, Stainless Steel – AISI 304 and AISI 316, Titanium
Size Range: M1.6 to M24 up to 200mm length. 2-56UNC to 1″
Torx Socket Head Cap Screw ISO14579
This is an improvement on the popular Hex Socket Head 
Cap Screw. Instead of an Allen drive, the Hexalobular drive or Torx eliminates the few shortcomings of the allen drive. Torx being a slipless drive is also able to take more tightening torque making this an extremely reliable screw option.
Low Head Allen Cap Screw 
Low head socket cap screws to Din 7984, often referred to as allen head bolts, have a hexagonal recess and is driven using a hex wrench or insert bit. These are designed to be used in special applications where head height clearance is a problem. Because of their reduced head height and smaller socket size, they normally cannot be preloaded as high as a standard socket head cap screw and should not be subjected to high dynamic loads.
Suitable for use in parts too thin for standard height socket cap screw and for applications with limited clearances