> The compact NATO one is 2 x 2, with sighting and lanyard holes. NSN-6350-99-613-9818

That's the BCB Mayday Signalling Mirror - I wouldn't recommend that - the reflected beam is pretty faint. I don't know what NATO was thinking.

There are two good polycarbonate 1.5"x 2.0" mirrors with retroreflective aimers:

They will both give you a bright, tight beam, which has not been my experience with the slightly larger BCB 2"x2" plastic mirror, which I've found to provide a faint, diffuse, beam.
Here's a comparison between the beams of the AMK Rescue Flash Mini and the BCB:


There is also the heavier, but more durable (and brighter) 2"x2" glass signal mirror with mesh retroreflective aimer made for Battle Systems LLC by S.I. Howard Glass, the company that makes the US military MIL-M-18371E 2"x3" and 3"x5"signal mirrors - product page here: http://battlesystemsllc.com/CESM.html



Edited by rafowell (10/07/17 07:04 AM)
Edit Reason: Connect to post above.
_________________________
A signal mirror should backup a radio distress signal, like a 406 MHz PLB (ACR PLB) (Ocean Signal PLB)