dsater:Did you get your stress relievers from McMaster? I was looking for those and couldn't find a place on line that actually "sold" them and I couldn't find them on McMaster.
I got them from a company called Seal Con USA. So far they've worked perfect.
If your light head has an added O-ring sitting on top of the bulb and then the glass lens on top of that I'd advise against diving with it. This was the original design for sealing the light head but we found out quickly that the edge of the bulb doen't take the pressure very well and will crack. Once it's cracked the light head will flood. I waisted several bulb connections trying to fix this problem but it was Andy, a member of my DIY site, that came up with the idea of adding a plastic ring to the lens which holds the added O-ring in place to seal against the outter edge of the Mag-Lite reflector housing. That evolved into the stepped lens which is what most people are using now.