For those who strive for improved trigger response and rate of fire performance, we offer the Cyclone Dual-Sector Gear System. The Cyclone Dual-Sector Gear, in addition to retaining all of the benefits of our standard gear sets, provides the following advanced features: Cyclone Dual-Sector Gear Evolutionary Dual-Sector design allows unprecedented ROF potential with two shots per sector gear cycle! Half-cycle cut-off system retains semi-automatic fire functionality. Dual short stroke design provides improved system efficiency for short barreled systems. Gear profile design ensures drop-in compatibility with PTW stock gear sets. The Cyclone Dual-Sector Gear System is designed for platforms with 363mm or shorter barrels. Due to super short stroked nature of the design, the system requires higher rate springs for operation. Cylinder set with a minimum of M120 spring rating is recommended.Specifications: Manufacturer Part#: G1T6Material: CNC Nickel Chromium Molybdenum Steel Gearbox Compatibility: PTW Only Click here for Gear Installation NotesNote: Professional Installation of Siegetek Gears Highly Recommended.