This AR15 Bar Barrel Nut is used to connect BAR style handguards to standard threaded upper receivers. This product comes with 4 shims to properly time the gas tube with the upper receiver.
Please Note: All Aero Precision Handguards use the BAR interface. If you intend to connect an Aero Precision Handguard to a standard threaded upper receiver, you will need a Bar Barrel Nut. If you have our M4E1 Enhanced Upper Receiver, you do not need a BAR Barrel Nut as the barrel nut and rail mounting platform are forged directly on to the upper receiver itself.