This Aero Precision M5E1 Handguard Barrel Nut is used to connect Aero Precision M5 Enhanced Handgaurds to standard AR10 & DMPS pattern threaded upper receivers. This product comes with 5 shims to properly time the gas tube with the upper receiver.
Please Note: If you intend to connect an Aero Precision Handguard to a standard threaded upper receiver, you will need a M5E1 Handguard Barrel Nut. You will need to select between an Aero/DPMS threaded barrel nut and an Armalite threaded barrel nut, depending on your upper receiver.
If you have our M5E1 Enhanced Upper Receiver, you do not need a M5E1 Handguard Barrel Nut as the barrel nut and rail mounting platform are forged directly on to the upper receiver itself.