Most Compact TAC 41 Variant 6000 Series CNC Aluminum Main Upper Receiver with Unique Serial Number POM Sliding Rings High Picatinny Rail for Mask Users Tapered Aluminum Outer Barrel (330mm, 6.05 Brass AEG Type) Quick Change Barrel (Bayonet Lock + Clamp Receiver Design) M24x1 Threaded Outer Barrel (Compatible with any M24x1 Muzzle Device) Includes 3 Barrel Spacers Fiberglass Reinforced Nylon Lower Body Construction Picatinny Stock Attachment Easy Hop-Up Adjustment 48 Round Capacity Steel Magazine Catch (AK Style) Stainless Steel 41 CC Cylinder/Bolt Assembly Stainless Steel Spring Guide with Thrust Bearing APS 13mm Spring Compatible, 90N Stock Spring Pre-Installed with Additional 120N Spring Included Quick Change Bolt System Stainless Steel Trigger Group (Sear, Spring Guide Stopper, Trigger Box, Safety Switch) Pre-Load Adjustable with Adjustable Two-Stage Setting CNC Aluminum Adjustable Hop-Up Chamber (TDC Design) AEG Hop-Up Rubber Compatible Anti-Double Feed System Comes with Lite Chassis and Lite Stock