SHS Steel piston gear designed to increase the rate of fire. The set comes with a tappet plate for V2 gearbox. The sector gear has two sets of 8 teeth so it pulls the piston and fires two shot in stead of the normal one shot per gear revolution. The gear is compatible with standard gear SHS 16:1 and 18:1. We recommend using a piston where all the teeth are metal. When installing the AOE should be done and also as the gear is not pulling the piston all the way back a stronger spring or spring guide spacers may be needed ( can be found in our gearbox parts section) This is suitable for use with an inner barrel with length of max. 300 mm.