Looking to boost your air rifle's performance? This heavy hammer spring is made specifically for the Air Venturi Avenge X and Avenger models — but heads up, it's NOT for the Bullpup Mk2 version. It's brand new from Alien Airgun Supplies and comes in its original packaging (might be simple, like an unprinted box). Think of it as an air plenum extension that helps with power tuning and consistency. Made right here in the United States, it's a custom bundle piece for tinkerers and shooters who want that extra edge. Whether you're target shooting or hunting, this upgrade can make a real difference in how your rifle cycles. Just make sure your model matches before you grab it!