Features and Specifications:Manufacturer Number: MI-SP18MMidwest Industries AR-15 SP-Series 18" M-LOK Handguard BlackSP-Series Suppressor CompatibleFree Float DesignHigh Quality MIL-STD 1913 Picatinny Top RailSeven sides of Magpul M-LOK compatible slotsMI Patented Torque Plate SystemBarrel Nut and Wrench IncludedConstructed from 6061 T6 AluminumFully De-Horned for non abrasive comfortable feelMI Lifetime WarrantyMade in America1.750" Inside Diameter2.0" Outside Diameter1.95" Over Mounting FlatsOverall Weight with barrel nut 16 ouncesHard Coat AnodizedColor: Matte BlackFits:AR-15 Upper ReceiversNote: Not for use in Gas Piston AR's, and certain AR-15 Billet Upper Receivers