A word of caution:
I'd been carrying the PCa as a backup light, and finally decided to test it in Mexico on a 100 foot dive. It wouldn't turn on at depth, and I tried -everything-. I stuck it back in my pocket and forgot about it for the rest of the dive, although I was quite a bit miffed. Later on the boat, it worked fine. Huh?? On a subsequent pool dive to 12 feet, it still ran OK. Was it just a fluke, or a design problem?
I've disassembled it a couple of times since the problem, and can find NO obvious mechanism for it not turning on at depth. I'd used it fine in Florida at 30-50 foot depths last year, and it ran trouble-free. It's been a great little light, but if I can't trust it at depth, it's gonna stay home with the other flashlights that aren't dive-able. Just imagine that you're in genuine trouble, and even your backup turns up dead...
The owner of one of our more technical shops dives the PCa as a backup, and hasn't had the same problem with it that I have, so something odd went on there. He's taken his down to around 200 feet without any issues, but I'm not certain he actually remembers *using* it at that depth. The spec sheet lists it for 300 feet max, but my experience would suggest a LOT more conservative depth rating.
Feel free to add flames, but it's a true report.