txwest; I didn't have to consider removing the O-ring as I did not find mines to be very tight. Also, I do need the waterproofness. A little story, as I went along with the cub scouts on a knee deep reef walk. Well, one thing led to another and we ended up being waist deep. I forgot that my keys were in my pocket and guess what was connected to them! Yes, my trusty ARC-AAA. Well, it survived it very well without any leaks. It must have been underwater for at lease 45 minutes. My other button battery LED light didn't do too well. I had to clean it up and change the button batteries. The salt water ate the insulating seals.
Gman; Yes, this is something I'm monitoring as I would like to see how the internal contacts holdup. As the old rule goes, the more complex, the more trouble. Will have to wait and see. But, I really am biased to this light as it looks like no other that I have seen. Heck, I was going to get it even if it was just bright, but it is really bright. This made it a happier purchase.