Here's a video from Magpul PTS about their new RM4 series that use KWA's ERG... "The PTS RM4 series of guns are variations based on the M4/AR-15 platform. The ERG (Electric Recoil Gun) RM4 system represents the continued evolution of the AEG (Automatic Electric Gun). Core features include a mechanical / electrical cut-off with the last round fired, functional bolt release, and simulated recoil via the proprietary Kinetic Feedback System. With its new feature set, the RM4 offers the shooter a degree of functional realism not present in previous generations of AEGs."