These are not navigation lights. The light fixture slides onto 3/4" tubing, and is not threaded. It is usually secured to the tubing by adhesive or a customer installed screw.
These lights can be used as general purpose cockpit lighting.

Tough polycarbonate Fresnel lens; Noryl plastic body
Brass bulb socket
Uses #90 miniature DC bayonet bulb (12V; 0.58A; 7.5W)