This is a 1/4" insert nut for wood. It is designed to mate with 1/4-20 screws.
The purpose of the insert nut is to provide a more structurally sound fastener for wood material. The insert nut will provide a much better hold than a general wood screw.
For use with 1/4-20 screw size
Dimensions: 13 mm (½") long.
Instructions: Drill 3/8” hole and install with a 6mm hex key.