Skintop911:
First and foremost, welcome to our community. Second, I do not believe this question violates any rules. You are merely requesting information. Not trying to sell something, which can violate rules, check with Chris K. about this and visit the forum rules pages for more info. Now to answer your questions.
I believe you have the Military Distress Marker Light known as the SDU-5E. Also known as an Emergency Beacon Strobe. These were normally issued by the DOD to all pilots as a part of their "survival gear" NASA also issues them to all astronaut crews. The main contractor for these was
ACR Electronics in Ft. Lauderdale FL. Incidentally, ACR builds a 406 MHz PLB, which Doug has mentioned on the equipped homepage. Look for the heading PLB. There is a newer model known now as the MS2000 on their website. I am not certain if it available to civilians or not. You may also find some information about them
here. and occasionally find them for sale on eBay. There is a replacement Battery cap for the Mercury stick battery and Battery cap, which allows for use with CR123 Batteries, such as those for the Surefire lights. I hope this helps.
Take care,
Stargazer
ASAP = Always Suspicious, Always Prepared