Polar Star JACK HPA Conversion Kit for M4/M16 V2 Gearboxes

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The Polar Star JACK is one of the easiest conversion options for turning any V2 M4/M16 style into one of the best performing airsoft guns on the field. The drop-in JACK cylinder replaces the cylinder assembly in most V2 center-line nozzle gearboxes. When connected to an HPA line, the JACK performs similarly to the Polar Star F1 in that it the pneumatic system is tunable for a wide range of rate of fire. Compared to the vast amount of moving parts in a classic gearbox, the JACK has only 1 moving part, the Air Nozzle, exponentially increasing the reliability vs. classic gear-driven AEGs. HPA provides instant trigger response even compared to typical AEGs using 11.1v LiPO batteries.


  • Tokyo-Marui V2 Gearbox Compatibility utilized by a wide variety of Airsoft rifle manufacturers
  • Adjustable FPS ranging from 280-500 FPS with 0.20g BBs (depending on barrel length and diameter)
  • Semi-Auto, Full-Auto, and Variable Burst fire modes
  • Variable burst firing programmable between 2 and 9 shot bursts
  • V2 M4/M16 Air Nozzle
  • Variable Rate of Fire from 1-30+ BBs per second
  • More air efficient than the stock Polar Star Fusion Engine operating at the same FPS.
  • Powered by High Pressure Air (HPA) via Remote Line & Tank (sold seperately)
  • Operating range of 40-130 PSI
  • FCU powered by 7-10v DC JST Connector Battery (sold seperately)
  • Made in the USA from durable Aluminum & Delrin 





Note: Complete TM Spec AEG rifle with gearbox, Regulated Air Rig, HPA Tank, Battery are required to utilize the JACK system.

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