Cpt. Mike Mei installed the Hephaestus Enhanced Recoil Spring for the Tokyo Marui AK Gas Blowbacks to his AKX and tests for sound and recoil improvements. The high-quality oil tempered chrome silicon steel wire used in this recoil spring ensures durability and longevity. Its enhanced spring rate and length are optimized for Green Gas (12kg Gas or above), delivering superior performance and a more realistic shooting experience with increased felt recoil. This drop-in upgrade is designed to replace the stock recoil spring in Tokyo Marui AK GBB Series models, providing a significant improvement in overall shooting performance. However, it is not recommended for use with HFC134A Gas.