This is "THE CLASSIC" when it comes to miniature reflex sights & for cloning all the cool SOCOM blasters - from pistols to RECCE builds. Evolution Gear did a fantastic job with this one, as opposed to the rest of clones, this one has correct screw size and functions like the real one.  
 
Notes:
Comes with RMR-correct screws (bigger than other airsoft clone RMRs) as it's a faithful clone to Trijicon's RMR. 
To turn on, hold + button for 5 seconds (as with a real RMR).