FX Impact M4 Compact PCP Air Rifle 500mm FX Smooth Twist X Superior (STX) Barrel System End of shroud is threaded 1/2' x 20 to accept a moderator (not included) Interchangeable Calibers and Barrel Liners (Sold Separately) Power Block 25" Overall Length Featuring the new FX Quick Tune System for nearly tool-free tuning Externally Adjustable AMP MKII (Adjustable Match Precision) Regulator Externally Adjustable Hammer Spring Tension with Macro and Micro adjustments  Externally Adjustable Valve Control 250 BAR (3,625 PSI) Max Fill Pressure 170 BAR max regulator working pressure Equipped with the 75cc Power Plenum 750 - allowing for an even wider range of power adjustment .22 and .25 cal M4's feature Dual transfer ports - one optimized for pellets, one for slugs Male Quick Disconnect Fitting Reversible Forward Mounted Sidelever Cocking Removable 300cc Carbon Fiber Air Cylinder (Additional Cylinders Sold Separately) Picatinny/Weaver optics mounting rail with 30 MOA compensation rides on 11mm dovetail allowing further customization to meet every shooters need Picatinny accessory rails below cylinder and on each side of the forearm New Quick Set Trigger - Adjustable match trigger Wika dual pressure gauges: one for air cylinder pressure, one for regulator pressure.   6.1 Lbs overall weight Height Adjustable Rubber buttpad FX UG1 AR15 style grip AR15 style manual safety Redesigned Side Shot magazine capacity*: 34 rds. in .177, 28 rds. in .22, 25 rds. in .25, 23 rds. in .30 Maximum Muzzle Energy: 25 FPE in .177, 45 FPE in .22, 60 FPE in .25, 80 FPE in .30 Includes one side shot magazine and 3 year transferable warranty *  - Older Side Shot magazines are compatible with the M4.  Tech Note: While the manual states the M4 models are capable of 300 BAR fill pressures, this is only achievable with aftermarket carbon fiber bottles. The current factory bottles from FX that are included on the rifles are rated for 250 BAR fill pressures and should not be filled over this pressure.