Professional Grade AR Upper Receiver Fixture. Robust fixture designed for years of hard use. Quick, intuitive interface that allows rapid building/rebuilding and repair of the entire upper receiver of the AR15/M16/M4 family of rifles/carbines/pistols. Designed to allow all upper receiver parts to be installed or removed without interference. Designed with rail systems in mind, the Device has clearance for most rail systems to allow installation and removal while the upper is securely held. Holds receiver from the inside via the bolt carrier raceway and charging handle raceway by way of a "T" interface. Front and rear lugs are controlled along with the entire bottom receiver flat Mfg: The Device Manufacturing.