An Allen Grub Screw, also known as a set screw, is a headless fastener designed to sit flush or within the surface of the material it's embedded into. It differs from the ordinary screw in that it has an internal hexagonal socket, normally tightened by an Allen key or hex key. By this unique design, it makes for tight and secure fitting without any projection, thus making it perfect f... https://www.dalloyedbolts.com/allen-grub-screw-manufacturers-suppliers-stockists-exporters.html