Samson SXT AR-15 M-LOK Handguard 15 inch Black. The simple clamping system uses two cross bolts which fit into the barrel nut for a rapid and easy installation. (The old SXS Series clamping system used a bias block on the bottom to secure the forearm to the barrel nut which required knurling). Specifications for Samson SXT AR-15 M-LOK Handguard: Manufacturer: Samson Color: Black Finish: MIL-A-8625 type III class 2 anodizing Fabric/Material: 6061-T6 Aluminum Gun Make: AR Platform Gun Model: AR-15 Gun Type: Rifle Handguard Type: Free-Float Gun Rail: Picatinny Included Accessories: Standard Inner Diameter: 1.25 in Outer Diameter: 1.6 in Mount Type: M-LOK Quantity: 1 Package Contents: Samson SXT AR-15 M-LOK Handguard Hex wrench Barrel nut Barrel nut wrench Samson 010612901: SXT AR-15 M-LOK Handguard 15 inch Black