This is KA Tech Airsoft's Carbon "Brusier” Type 1. It uses handcrafted carbon and aluminum together to create the ultimate CQB M4 Internals are finely tuned to work together as one cohesive unit. If you'd like to swap out any of the parts for different ones such as an HPA engine, trigger, Hopup, etc, please let us know. Polarstar Jack Retro Arms Hopup Maple leaf bucking Flat Hop ZCI 6.02 200mm inner barrel "Bruiser" is a handcrafted Polarstar HPA rifle made for CQB and fast paced playing with its lightweight design. It shoots a perfect 300FPS at 100PSI with a .25g bb. Carbon barrel AND stock lengths can be chosen from 6-12in (both 8 inches as shown) All KA Tech Airsoft rifles come as shown with FCU & Battery.