Small light is T4W Large Light is R2 (Bilux)

Solid aluminum base. Sits flat on workbench. Steel preload pin. Steel threaded studs. This sets the preload to 14MM. I have 1MM shims I can send you in order to set the preload to 13MM. 14MM was used on the early dome top pumps. 13MM was used on the square top pump.