The Aero Precision M5E1 Handguard Barrel Nut allows you to connect an M5 Enhanced Handguard to standard Armalite and DPMS pattern threaded upper receivers. These AR15 Lower Parts by Aero Precision are specially made to connect M5 sized handguards to standard sized upper receivers - select the right size for your build! The Aero Precision M5E1 Aluminum Barrel Nut feature a Melonite finish so that it will last as long as you do. Install an Aero Precision M5E1 Handguard Barrel Nut - Threaded Barrel Nut and create a combo that outperforms the competition. Please tighten down the barrel nut to 65 ft lbs with a standard AR15 armorer's wrench. Specifications for Aero Precision M5E1 Handguard Barrel Nut: Manufacturer: Aero Precision Additional Features: Threaded Color: Black Gun Model: DPMS M5 Condition: New Fabric/Material: 7075-T6 forged aluminum Quantity: 1 Finish: Anodized Black Included Accessories: Shim Pack 5 shims Weight: 2.24 Country of Origin: USA Package Contents: Aero Precision M5E1 Handguard Barrel Nut Shim Pack (5 shims)