Description from American Science & Surplus
Cage the wild light bulb in order to protect it from its natural enemy, Vandalus urbanosa. Unlike the domestic indoor bulb which can be protected with a silk or paper shade, this more-endangered bulb is found outdoors or in rugged industrial habitats. Our yellow-plastic cage is available for bulbs of 100 watts or less. (Bulb should not touch plastic.) This cage is 6-1/2″ long x 5″ dia at its widest point. One side has a release latch for access to the bulb. It fits over a medium-base socket to protect the lamp in it. Hardware included.