Emerson Functional MS2000 Strobe Light
No need to buy a dummy ACR MS2000 strobe/distress marker as EB Airsoft now has in stock a working replica from Emerson. Costing US$35.65 with free shipping included, this one's powered by AA Batteries. We don't know how this can stack up against the real ACR M2000 though this one has a flash rate of 50 ± 10 per minute.
Is this waterproof? Don't take chances of dipping it in water but it does seem to have a directional blue filter. In terms in brightness, we cannot tell too, but if you go for the original you get 250,000 peak lumens with the strobe.