Rainier Arms Rainier Industries Pro Series Mk2 Quad-Rail AR-15 Handguard Black 11.75 in. To achieve this we designed it an extended aluminum barrel nut and larger stainless steel mounting lugs for better rigidity to maintain a mechanical zero. The Pro Series Quad rail built to stand up to the rigors and demands of what your duty weapon requires. Specifications for Rainier Arms Rainier Industries Pro Series Mk2 Quad-Rail AR-15 Handguard: Manufacturer: Rainier Arms Color: Black Finish: Mil Spec Type III Hard Coat Anodized Fabric/Material: 6000 Series Aluminium Gun Make: AR Platform Gun Model: AR-15 Attachment Type: Picatinny Features of Rainier Arms Rainier Industries Pro Series Mk2 Quad-Rail AR-15 Handguard CNC machined 6000 series extruded Aluminum Hard Coat Anodized Milspec Type III Class 2 Black Barrel Nut is 7075 Aluminum steel wrench and mounting hardware included No Barrel nut shims required for installation Weight: 19.2 oz 1.31 in interior diameter 2.2 x 1.97 outer dimensions Full length picatinny rails with laser engraved position marks at the 3 6 9 and 12 oclock positions Compatible with most known low profile non-adjustable and adjustable gas blocks Package Contents: Rainier Arms Rainier Industries Pro Series Mk2 Quad-Rail AR-15 Handguard Barrel nut and hardware Rainier Arms RA014: Rainier Industries Pro Series Mk2 Quad-Rail AR-15 Handguard Black 11.75 in