Socket bolts with hexagon interior are made cylindrical or countersunk head which has a hollow hexagonal allen wrench for the head part. These socket bolts are used as hexagon in the machinery industry.
These bolts are also used the clamping special dies. The bolts may also have grooves, can be low head and a guide that head.
The bolts can also have grooves, be low head and have a guide on that head.
CYLINDRICAL HEAD LOW
CYLINDRICAL HEAD LOWER GUIDE