Carbide lamps are amazing but I always figured they'd blow out if used in non-cave environment. Dunno. Come to think of it, my long-departed carbide lamp was a Justrite. Getting rid of spent fuel a nasty trick.

Regarding the 1970s USFS Justrite headlamp, mine took four D-cells, and a rather large and primitive-looking bulb. Whatever its many faults, it was easily the brightest battery lamp I've ever used.