[About Socket Cap Screws:]
The hexagonal head socket cap screw is widely used among all kinds of screws and is relatively high in requirements.
Advantage is that
1) the fastening force is relatively large,
2) and it can be operated by using an Allen key so that easy to install, almost used in a variety of structures,
3) The appearance is relatively beautiful and tidy.

The disadvantage is that the fastening force is lower than the outer hexagon, and the repeated use of the inner hexagon is easy to damage.