Air Efficient EKO Valve System (Patent Pending) shoots up to 1500 shots from a 20 oz CO2 tank-Anodized Matte Finish-All Aluminum Extruded Body * High Impact Polymer Clamping Feedneck-Standard CA Thread Vertical Adapter-Pull Pin Top Cocking Delrin Bolt * Tool-Free Striker Plug Design-10" Micro Ported Barrel-Ergonomically Designed High Impact Polymer Trigger Frame * No-Slip Rubber Grip Panel-Two Finger Trigger-External Velocity Adjuster * Steel Braided Hose Line-Inline Bottom-line ASA-Operates on CO2 or Compressed Air