This housing is to be used with a 3-pin harness, an H13 bulb, and appropriate terminals for substituting vehicle system circuit loads when assessing circuit behavior. The H13 bulb's tabs provide sufficient friction to hold the bulb in the housing. You will have to turn the bulb ears with some force to seat the bulb. The bottom rests on the fillet leading to the bulb lock tabs.
The author marked this model as their own original creation.