A socket cap screw, also known as a socket head capscrew, socket screw, or Allen bolt, is a type of cap screw with a cylindrical head and hexagonal drive hole. The term socket head capscrew typically refers to a type of threaded fastener whose head diameter is nominally 1.5 times that of the screw shank (major) diameter, with a head height equal to the shank diameter.
Socket head cap screws are used for applications with limited space. They have cylindrical head and internal wrenching features (mostly hexagon socket) that allow them to be used in locations where externally wrenched fasteners are convenient.
Technical Parameters:
| Size | M4mm | Material | Zink plated steel | |
| Hex key size | 3 mm | Thread type | ISO metric coarse | |
| Strength Class | 8.8 | Weight (100pcs) | 0.17 ÷ 0.57 kg |
