A Brass 1/2" internally threaded coupler used to join two male threads together. This Brass 1/2" Coupler is 3/4" long. Ideal if you have a 1/2" male stud on the lamp and you want to extend the height of the lampholder. Add to this a Allthread to then add the 10mm lampholder.
1/2" tall with a 3/4" internal thread.