Help Center

New to HPA?

So, you're interested in trying out this HPA thing but want to find out more but want to find out more before you take the leap. Check out our FAQ to better understand the basics of what is needed to make a conversion possible.

Will a PolarStar HPA conversion fit my rifle?

It can be frustrating to purchase upgrades only to find out that they don't fit your particular rifle. To make things easier we have compiled a database of information on compatibility of the various PolarStar HPA conversions into a wide range of models.

What HPA system do I choose?

Gearbox Version - The first step in selecting an HPA conversion kit is to determine which gearbox "version" your AEG uses. Over the years, AEG manufacturers have created various gearbox versions suited to the shapes of different real firearms. In the case of our cylinder conversion kits such as the F2, the gearbox version will determine what switchboard model will be required to interface with the trigger and selector components. Since the Fusion Engine replaces the entire gearbox the "version" will determine which Fusion Engine model can fit into the replica.

Nozzle Type - It is important to know whether the nozzle of the AEG is centered in the cylinder (V2, V3, M249, etc..) or if it is offset vertically (M14, SVD). This will determine which HPA systems are compatible with your AEG. At this time, only the F2 supports AEGs with offset nozzles. Offset nozzles have a "O" prefix before the number.


I don't see my gun listed in the table.

In many cases a replica of the same brand and product line (VFC ES Series, G&G CM Series, etc..) will use the same internal components and compatibility for all models in the series will be the same. Generally, compatibility will be the same for replicas of the same model even if they are from different manufacturers as long as they use the same gearbox version. For example, the Version 2 / M4 kit is compatible with almost all M4 replicas with very few exceptions.

If you do not see your replica (or a similar model) in the database there may already be a compatible "Standard Nozzle" which will work. Please see the Standard Nozzle Chart for the system you are interested in (F1/JACK/FE) to calculate the recommended nozzle length for your replica and to check if the nozzle length is already available. If it is not, we will gladly machine a custom nozzle for you.