This is specail Max Valve kit system for AEA Bigbore Challenger Airguns, It will maximize the power output on Challenger Bigbore alomost 80% up Before Installation: .357CAL 140 GRAINS1000 FPS 10+ GOOD SHOTS 300 FPE UP .457CAL 300 FPE UP235 GRAINS 850 FPS 6+ GOOD SHOTS 400 FPE UP .50CAL 235 GRAINS 850 FPS 6+ GOOD SHOTS 400 FPE UP After Installation: .357CAL 140 GRAINS 6+ GOOD SHOTS 350 FPE UP .457CAL 300 GRAINS 4+ GOOD SHOTS 630 FPE UP .50CAL 300 GRAINS 4+ GOOD SHOTS 680 FPE UP .510CAL 300 GRAINS 4+ GOOD SHOTS 700 FPE UP