Hurricane Metal Body with Metal Hop Up unit for M4 Series. Highly refined finishing with high precision seams and tolerances makes for an extremely high quality fit right out of the box. High quality aluminum construction on par with Systema metal bodies. Laser engraved markings and logos on both sides of receiver. SR16 logo. Functional ejection port flips open when you pull the charging handle back. Hurricane is the only metal body maker on the market that retains this feature on their metal bodies.