The R-ONE handguards are designed with size and weight in mind, while still providing plenty of real-estate to accommodate any attachment needs the end user may have. Aero Precision's proprietary ATLAS attachment system is a durable and dependable mounting platform, maintaining a slim profile while still providing the strength and stability customers have grown to love from Aero Precision handguards. This complete upper does not include a BCG or Charging Handle.Includes:M5 Assembled Upper ReceiverM-LOK ATLAS R-ONE Handguard of choice18" 6.5 Creedmoor SS Barrel, Mid-LengthLow Profile Gas Block and Rifle Length Gas TubeProduct comes assembledM5 Assembled Upper Features:Forged from 7075 T6 aluminumM4 Feedramps.2795 takedown pin holesLaser engraved T-marksDPMS High Profile (.210) Tang)Includes port door and forward assistATLAS R-ONE Handguard Features:Full top picatinny rail for optional attachmentsQuick disconnect sling socket at the 3, 6 and 9 o'clock positionsCompatible with low profile gas blocks1.5" Inside diameter1.75" Outside diameterCompatible with AR-308 Upper Recievers with a thread pitch of 1-7/16 x 16 along with a DPMS High Profile (.210) Tang Rail18" 6.5 Creedmoor Stainless Steel Barrel Features:Twist: 1 in 8Threading: 5/8 x 24Material: 416R Stainless SteelFinish: Bead BlastedGas Block Journal: .875Gas System Length: Rifle LengthWeight: 61.5 ozDPMS Barrel ExtensionHP and MPI Tested