Also known as a flat-heat screw, a countersunk screw is a type of screw that's designed to rest flush with the object or surface in which it's inserted. ... Countersunk screws are simply characterized by their flat head, which allows them to sink into objects and materials.

What are countersunk heads used for?

A common use is to allow the head of a countersunk bolt, screw or rivet, when placed in the hole, to sit flush with or below the surface of the surrounding material (by comparison, a counterbore makes a flat-bottomed hole that might be used with a socket-head capscrew).

What is a countersink head?

A countersunk screw head is characterized by its ability to rest flush with the surface into which it's installed. The head essentially “sinks” into the workpiece's surface. If you inspect a countersunk screw head, you'll notice that it tapers towards the shank.