The US Coast Guard seems to like the ACR "Firefly 2" strobe.

In this USCG training video for the skill task:
"BCM-02-08-ANY Identify Boat Crew Survival Vest Equipment"
the strobe the instructor shows at 0:40-0:43 is an ACR Firefly 2.

http://www.youtube.com/watch?v=hq7bOZxNJR4



The USCG is also displaying several of the ACR Firefly 2 at 00:09-00:11 of
this survival suit demo (and the interviewer discusses this in 2:00-2:32 of this segment)

http://www.youtube.com/watch?v=SQxyr2fIu0c


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A signal mirror should backup a radio distress signal, like a 406 MHz PLB (ACR PLB) (Ocean Signal PLB)