The Lucas MAXLITE

Among the things that I inherited from my father were several versions of the UK wartime headlamp mask, for air raid black-out purposes. Looking through the various designs the example pictured below stood out among all the others in that it only has one slit for letting any light out from the vehicle's headlamp, yet, comically, the makers thought it appropriate to label it "MAXLITE". I think that it would have been better and more honest to describe it as "MINLITE". All of the other headlamp masks that I own have more than one slot for letting light out.