This barrel kit has extreme tolerance (12.7mm/.5inch bore) to increase the output of the TR50/HDR50 to 30 to 40 Joules when combined together with the power kit. Without the power kit you will get 20-30 Joules. The barrel kit comes in 2 parts, the barrel with a thread protector and the 4 inches barrel extension. Add on the barrel extension increases 3 to 5 Joules.
The final power output is depending on the type of air and ammo used.
Made in Germany
Installation help https://www.youtube.com/watch?v=rAu7CWbBZ0A
NOTE: By installing this barrel to your TR50 , your factory warranty on your TR50 will be voided.