SKU: 91695745532

PolarStar Airsoft JACK Electro-Pneumatic Gearbox Conversion Kit - V2 for M4

Sale price$216.00 Regular price$240.00
Save 10%

Pay in installments of $60.00 with ShopPay, AfterPay and Klarna

Shipping Estimate
USA
  • USA
  • CAN

Ships within 48 hours · Estimated delivery Aug 8 - Aug 13

Promo Codes Available:

For Your Every Summer RSVP, with Code: SUMMER15

Description

PolarStar Airsoft JACK Electro-Pneumatic Gearbox Conversion Kit - V2 for M4The JACK system was designed to answer the demand for an affordable, high performance HPA (High Pressure Air) conversion for AEG's. The system is a drop in cylinder replacement that is universally compatible with a wide range of gearbox versions that have center line nozzles. Similar to its sister product, the F1, it replaces the original gearbox components with a programmable pneumatic system allowing for higher performance and greater reliability

The JACK™ system was designed to answer the demand for an affordable, high performance HPA (High Pressure Air) conversion for AEG's. The system is a drop-in cylinder replacement that is universally compatible with a wide range of gearbox versions that have center-line nozzles.

Similar to its sister product, the F1, it replaces the original gearbox components with a programmable pneumatic system allowing for higher performance and greater reliability over a gear driven system. Although economically priced, JACK™ still retains the same performance and quality you have come to expect from PolarStar products.

JACK™ has only 1 moving part, the nozzle, which acts as its own poppet valve which is piloted by the solenoid. With the exception of the poppet being integral to the nozzle, the valve is similar to the poppet valve used in the previously released Fusion Engine™ and is what gives JACK™ its signature muzzle report. The system itself only has 6 parts and can be completely disassembled by hand in a matter of seconds so the system is very reliable and easy to maintain.

Just like all other PolarStar HPA conversions, JACK™ also allows for easy velocity adjustment. Using a standard M4 as an example, velocity can be adjusted from below 280fps and up to approximately 500fps with a .20g BB. This can be done simply by adjusting input pressure and poppet dwell to fine tune your rifles velocity in increments of just a few FPS at a time. Maximum velocity potential of the system will vary depending upon the barrels length and tightness of the bore. Longer and tighter barrels will yield a higher velocity while shorter or wider barrels will be yield a lower velocity.

As with all of PolarStar's electro-pneumatic conversion kits, you can quickly change and adjust key functions of JACK™ via the on-board FCU (Fire Control Unit) which is no bigger than an AEG's MOSFET and can easily fit inside of a rifles battery compartment along with a small Li-po battery. Using the FCU's five position joystick and LCD display you will be able to easily and precisely adjust such functions as the systems cyclic rate, fire modes and poppet dwell on the fly.

Although efficiency was not a critical requirement during development, JACK™ does boast some highly respectable figures in this category. This is made possible by is compact and intelligently laid out design which minimizes dead volume resulting in better air flow, faster response and less air used per shot. As a result JACK™ is considerably more air efficient than a bone stock Fusion Engine™ when operating in the same velocity range.

HPA system not included
Features:
Designed, manufactured and built in the U.S.A.
Assembled from CNC machined aluminum components with high performance delrin nozzle
Universal cylinder design is compatible with numerous gearbox versions
Optimized flow profile, firing point and flow path promotes superior shot consistency and accuracy
Capable of functioning in damp and sub-freezing climates without affecting performance or reliability
User selectable Semi/Full Auto, Semi Auto Only and Variable Burst modes
Independently adjustable velocity and cyclic rate
Auto Switch mode allows for proper selector configuration for specific models
Easy to use Fire Control Unit (FCU) with LCD display and five position joystick
Instantaneous trigger response. Faster than an AEG with a Li-po
Material: Aluminum / Delrin
Compatibility: Tokyo Marui Spec Version 2 Gearboxes
Included Nozzle Type: M4 series 
Rate of Fire: 1 - 30+ RPS (Adjustable)
Muzzle Velocity: 500 FPS w/ .20g 6mm BB @ 120 PSI
Fire Modes: Semi / 2 - 9 Round Burst, Semi / Full Auto, Semi Only
Power Source: HPA (High Pressure Air via Remote Air Rig)
FCU Battery: 7-10VDC w/ JST Connector
PSI Operating Range: 40 PSI - 130 PSI (Do NOT exceed 130 PSI, otherwise you may damage the internals)
Package Includes: Pre-Assembled JACK Conversion Kit
Battery: 7.4v-9.6v NiMH or Lipo (Not included).

Manufacturer: PolarStar Airsoft

Required for Operation:Complete TM Spec AEG rifle with gearbox, Regulated Air Rig, HPA Tank, Battery (Sold Separately)

Installation: JACK™ will be installed into the shell of your AEG's gearbox. The only parts which you need to retain from your gearbox is the trigger w/ spring, safety assembly and selector components. Retain the original spring guide for models which require that the stock be secured to the gearbox and not the receiver.

Compatibility Disclaimer: The Version 2 kit is compatible with most TM Spec AEG's in that rifle series. This kit is compatible with other TM Spec rifles which use a Version 2 gearbox with the traditional open contact trigger switch. In most cases only a model specific nozzle is required to install the system into another model . If your rifle has an electronic micro switch (i.e. Ares Amoeba) you will need to purchase the kit for that specific model series which will include a different switchboard.

Disclaimer on High Pressure Air (HPA) Systems:Only HPA or Nitrogen should be used with the JACK™ system. CO2 and Propane cannot be used. Using liquid propellants such as this can result in damage to the system.

HPA Tanks are a safe and effective source of power though there are some precautions you must follow. Please follow these proper precautions when using HPA systems:

  • NEVER put oil in the fill valve of the tank, or else the tank can combust on refill and serious injury can occur. Lubrication is not necessary in HPA systems.
    - ONLY allow properly trained professionals to fill your HPA tank.
    - ALWAYS double check your Regulator pressure. Never raise the regulated pressure above 120 PSI
    - Make sure to have your tank Hydro-Tested when necessary. (Usually 3-5 years from date marked on tank, depending on make and model)
    - Be sure to properly transport your HPA tank. Store in a safe, secured place when in a vehicle, and be sure to stow in a bag or tank cover when in use. Avoid dropping the tank on hard surfaces as this can seriously damage the tank and lead to failure.
    - Always turn off the tank and bleed the air line when you are done. This will ensure a longer tank and system lifespan.

 

Shipping Notes
  • Free Standard Shipping on $100+ Orders to the USA.
  • Except Preorder products are shipped in 48 hours.
  • Delivery to the USA:
  1. Standard Shipping : 3-10 business days
  • If time is of the essence, please consider selecting expedited delivery for faster service.
Exchange/Return Notes
  • We offer a 30-day return/exchange service after receiving.
  • Final sale items are not eligible for returns or exchanges.
  • To process your return/exchange, please contact us at [email protected]
  • Please click here for more details>>> Return & Exchange Policy
SKU: 91695745532

Discover Niche Categories That Outsell

Top-Converting Item to Boost Your Average Order

4.9 ★★★★★
Based on 21 reviews
Sort
Highest Rating
Newest First
Oldest First
Product Reviews
A
Verified Purchase
Alice
Pawtucket, US
★★★★★ 5
Best dog toy!
Color: Multicolor/Alligator & Wild Duck, Size: Medium, Color: Multicolor/Alligator & Wild Duck, Size: Medium
Best dog toy! Most dog toys lady maybe a week or less but this one has been going strong for almost 2 months. Both the squeekers still work on both toys i purchased. My vizsla loves ti squeek and carry it around. We added an empty water bottle in the pocket cavity for some extra fun! Yes, we are still on the same water bottle! Fantastic durability.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 26, 2026
A
Verified Purchase
Amy Jo
Natrona Heights, US
★★★★★ 3
Shows wear quickly
Color: Multicolor/Sheep & Cow, Size: Medium
These are cute but not holding up as well as I had hoped. Quality is ok and the Velcro has held up great. The fabric just isn’t as good as it could be. They are much larger than expected.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 28, 2026
R
Verified Purchase
Rachel
Port Orchard, US
★★★★★ 5
Super Sturdy with hours of fun.
Color: Wild Duck, Hare, Squirrel & Alligator, Size: Small
I got the small ones that you cannot put a water bottle in. These toys have held up way better than expected. I am dog sitting a very rough with toys dog named Chunk. He tears up ever. Single. Toy my dog (Ted) has. I bought new ones just for chunk. These appealed to me with the no stuffing, They were cheaper, and have a squeaker. Everything chunk needed. They arrived on time and I thought I wasted my money. They were super soft, like too soft. They felt flimsy and weak. Like 5 minutes with chunk and they be dead. 2 hours with my dog and they would have a rip. So far 2 of them (I set two out) have lasted the whole weekend. The bunny looks very rough and disgusting, but no rips, the squeakers still work, and no random fluff everywhere. I am going to wash the bunny once chunk leaves. My very careful doggo Ted loves them too. He throws them up in the air and catches them, plays tug of war with them, and no rips. They are super sturdy. He can’t wait until Chunk leaves (chunk is 2 and Ted is 12-13) so he can play with them.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on April 26, 2026
A
Verified Purchase
Amber B.
Houston, US
★★★★★ 5
Loved it
Color: Brown/Wild Duck, Size: Large, Color: Brown/Wild Duck, Size: Large
He loved it so much, he destroyed it so we ordered another. I didn't realize that you can stick an empty water bottle inside. Again, the first one didn't last long, but he enjoyed it
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 20, 2026
D
Verified Purchase
Doug Jones
Cuba, US
★★★★★ 5
Very fun interactive toy
Color: Brown/Wild Duck, Size: Medium
This toy is very versatile. There's no stuffing yet it's very soft so it can be used as a tug toy. It also makes for a fun fetch toy because it has a cavity to put a water bottle. It gives your dog something that crinkles and can be pierced when bitten and easily replaced with another empty bottle whenever necessary. That is what really makes this toy the standout of all the ones offered by Best Pet imo. I don't expect this to last forever but once my pup gets bigger we'll probably get the large size for her because there's not too many all in one fetch and tug toys at an affordable price.
WAS THIS REVIEW HELPFUL?YesReportShare
Reviewed in the United States on May 15, 2026

recommand products