A flashlight that includes a substantially watertight battery housing, a bulb mounted in a socket assembly, a reflector, and a lens covering a forward end of the reflector. A plurality of batteries are supported in the housing so that only if the batteries are correctly polarized will a circuit be completed...http://www.google.es/patents/US5904414?utm_source=gb-gplus-sharePatente US5904414 - Flashlight with gas permeable membrane and battery polarization
Flashlight with gas permeable membrane and battery polarization
