This is a replacement for the headlight adjusting screw/nut assemblies used with old-style sealed beam headlights. The originals had the nuts made of plastic that snapped into a metal plate behind the bulb. Because of the proximity to the hot headlight, and the fact that many of these are over 50 years old, leads to plastic deteriorating. All the replacements I've found are so cheap that the barely stay in place. This is designed to be used with the original screw, and a new standard nut.

Print without support material, big side down. Use a soldering iron to press a new nut into the hexagonal recess that matches the old screw (usually 1/4x20). Insert the assembly into the square hole in the plate from the backside, then use a soldering iron to mash over part of the square protruding through. This holds it in place when installing the screw and headlight. Good luck!