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. ... Therefore, when you drive a countersunk screw into an object or surface, the head will sink so that it's flush with the respective material.

What are countersunk bolts used for?

Countersunk bolts are used when a smooth surface is required. Common applications include bridge decking, walkways, and railing.

What is a countersink screw?

What Does it Mean to Countersink a Screw? ... When you drive a screw into any material, you typically stop when the screw head hits the surface. To countersink that same screw means you are going to drive it below the surface.