The New Gen 8 M4A1 is often a best-of-the-line gel blaster, made up of casted metal gears and metal piston, a metal internal barrel as well as a higher strength gearbox when compared to the previous version of Gen 8. https://kkgelblaster.com/collections/best-sale/products/kkgelblaster-fjs-m4a1-cqbr-gel-blaster