The 50W lamps that come with the Optronics lights have their own lens. The metal shells are simply shells. Check the physical dimensions of the lens-less lamp and see if it has the same dimensions as the ones that have lenses. The lens-less ones may not fit right and rattle about or something. See if it works, and if it does, fine, but don't take it out in the rain.

I am also of the opinion that you need to have a lens to protect the hot lamp from moisture. A water drop hitting the hot glass will cause it to shatter. Not good if you're out in the middle of nowhere at night, in the rain... or a stupid bug smacks into it.

O.T. A Boy Scout thing would be to see if you can use the lens-less lamps to start a fire. A little tinder in the reflector, turn on the light and poof! Instant fire. I don't know...whatever... its late... or is that a McGuyver thing.