Engineering:Dimpler
From HandWiki
A "Dimpler", also known as a drywall screw setter, is a #2 Phillips screwdriver tip usually 1 inch (25 mm) long with a stopper. It is used to stop the drywall screw from penetrating the drywall.
This tool is mostly used by non-professional installers, but some professionals will use this tool for small patch jobs.[citation needed]