The base gun is a Valken Mod-M M4. Internals: -ASG Infinity 18k motor -POM Oring nozzle -Metal Cylinder Head -Polished Brass Cylinder -SHS Aluminum Bearing Piston head -SHS Piston -M150 Spring -SHS DSG Sector gear -Upgraded Tappet plate spring -Metal Spring Guide -CNC Blue Trigger -Rotary Hopup -Wired to deans Specs: ~25rps w/11.1v 1200mah 25c lipo ~330fps w/.25g ~360fps w/.20g This gun runs off a Burst Wizard 4 Hardwired Mosfet that has tons of tuning options(program instruction sheet included) The function of the gun is a 2-stage trigger but it works by time delay not trigger pull distance. Its a very neat way to go about achieving semi auto with a dsg and not use an expensive mosfet.