This is a genuine Dewalt replacement part designed for use with a variety of power tools. It is a standard hardware which has multiple applications based on your tools. This is a metal torx T-10 screw which is sold individually.
This is a genuine Dewalt replacement part, it is sold in individually with the mounting screw. The Dewalt Belt Hook is attached to the bottom of the handle assembly on the tool model numbers shown below. Its purpose is to hook the tool to your belt when not using the tool.