Product Overview The Kythera SA HPA Conversion Kit is one of the most innovative and anticipated products ever released by PolarStar. This system represents a complete departure from traditional HPA engines. The Kythera does not use a battery, an FCU, or any electronics. It operates as a fully mechanical HPA system, offering unmatched reliability, realism, and durability. Because it contains no electronics, the Kythera is completely waterproof. Players never need to worry about charging batteries, protecting circuit boards, or dealing with electronic failures. This makes it ideal for harsh environments, milsim events, and long game days. Fully Mechanical Semi-Auto System The Kythera SA is the semi-automatic only version designed for AEG gearboxes. It was engineered from the ground up as a mechanical system. Every function happens through physical components rather than software or electronics. This approach delivers consistent performance and mechanical reliability in all conditions. Realistic Single-Action Trigger System What truly sets the Kythera apart is its realistic trigger mechanism. The trigger replicates the function, weight, and feel of a real single-action firearm. Hardened alloy steel sears catch and release a stainless-steel spool valve in the same way a real firearm releases a hammer or striker. This design creates a distinct trigger break and reset. The trigger feels real because it is real. Users can adjust trigger weight and over-travel to fine-tune feel and response. The balanced firing valve ensures trigger feel remains consistent regardless of input pressure or velocity. Complete Closed-Bolt Shot Cycle The Kythera completes a full shot cycle during the trigger pull. This provides the proven closed-bolt performance found in the Fusion Engine and F2, but in a fully mechanical system. The nozzle chambers the next round and refills firing volume automatically, without requiring trigger reset. This allows fast follow-up shots, quick cycling, and a reduced risk of double feeding. The system is ready to fire again immediately after each shot. Exceptional Efficiency and Consistency The Kythera valve operates without a pilot valve. This means 100% of the air entering the system fires through the nozzle. The result is extreme air efficiency and shot-to-shot consistency. The valve releases at the same point every time, with the same force, regardless of trigger input. Universal Charging Cord A steel charging cord at the rear allows manual cocking of the spool valve if air pressure drops below operating range. This feature adds redundancy and reliability. The cord can be routed through the grip or linked to the charging handle. Easy Installation The Kythera installs as a single unit into a standard AEG gearbox. No gearbox modification is usually required. Only the trigger, spring guide, selector, and safety components are retained. Wide Velocity Adjustment Range The system operates from 60 to 180 PSI, allowing FPS tuning from CQB to sniper roles. Testing shows approximately 270–500 FPS with .20g BBs using a 6.05×380mm barrel.
