Aero Precision APCR640476: The Aero Precision M4E1 Pro Alpha Series rifle is the first entry into the M4E1 PRO lineup. This launch edition rifle comes available in a special configuration that is only available in a limited quantity. The basis of the M4E1 PRO lineup is the M4E1 PRO Lower Receiver. This receiver seamlessly integrates ambidextrous controls into the flagship M4E1 Lower that allows for the shooter to easily operate the bolt catch, magazine release, and safety without modifying their dominant firing hand. The upper receiver includes our new MOD 4 handguard that was designed to be as robust as possible while still maintaining a slimline profile.