This is the new Spring 3 Shot Combat Tactical Pistol Grip Airsoft true to life shotgun. The UTG M3 shotgun is modeled after the well known Marui M3 Shorty which has been in service for several years.
This is built into the K4020U MOSFET amplifier in order to display amplifier power output. The meters are mounted behind the correct scale which is also illuminated according to the speakers connected to the amplifier (4 or 8 ohms). When the amplifier is switched into a bridge configuration then both meters may be connected in series.