Original ceramic cap for the Adjust a Wings reflectors.
You can buy it as a spare if you have broken or damaged the one that you had of your reflector, or it also serves for when we have the Adjust a Wings big size. So you can put two bulbs to the same reflector taking advantage of its size.
Valid for thread E - 40, which is the one that comes with high pressure sodium and metal halide bulbs of 250. 400. 600 and 1000 W used in indoor crops and greenhouses.