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. Our 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.Includes:M5 Assembled Upper Receiver - Anodized Black15" ATLAS R-ONE M-LOK Handguard18" .308 CMV Barrel, Rifle 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" .308 CMV Barrel Features:Twist: 1 in 10Threading: 5/8 x 24Material: 4150 Chrome Moly VanadiumFinish: QPQ Corrosion ResistantGas Block Journal: .750Gas System Length: Rifle LengthWeight: 52.35 ozDPMS Barrel ExtensionHP and MPI Tested