Its my "critter light"
Where I dive, there are lots of Octos. I don't want to zot an octo with a 21w laser, so I put on the critter light. They also are very useful in reading my bottom timer in a white out, shining on wetnotes without getting a face full of 21w reflection off the pages, etc.
I dived with them for years. Never got in the way, no worries.
However, I have since figured out that if I lace my hand over the light head and let just a couple of streams filter through my fingers, I get about the same effect - meaning I won't fry an Octo's eyes. So I do that now and leave the critter lights at home.
BTW - I've tried about everything you can try to clean these reflectors (WD40, Lemon Juice, Cymbal Cleaner, Car Polish) - there's a whole thread on this I ran through on SB not too long ago - I couldf find nothing that would work to bring them back.
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Ken