A rectangular metal lamp, with a handles and a clip to attach to the front of a bike. There is a brass on/off switch on the top and a mechanical knob to turn up a red glass to cover the lens. The detachable top and bottom work are held in place by push-in pins that then pop out and lock the pieces in place. Possibly WW1.
Context
There were rules that had to be obeyed in the black out if you rode a bicycle:
Regulation white patch on mudguard.
Good tyres and brakes.
The rear lamp must have only one aperture - no bigger than a one-inch circle, the light from which must be clearly visible from 30 yards but not visible at 300 yards.
The upper half of the front lamp glass and whole of side or rear panels must be completely obscured and lower half of reflector must be painted with black matt paint of otherwise rendered ineffective.