This power kit increases the output of the HDX to 30 to 40 Joules.
The final power output is depending on the type of air and ammo used. You have to open up the gun to install it. This shouldn't be installed on the 36 Joule HDX68 only the 12 Joule.
Install instructions from Mad Dog Airguns: Fitting a Powerkit68 to the Umarex HDX 68 - YouTube
Made in Germany
GUN NOT INCLUDED