ATLAS The new Aero Taper Lock Attachment System (ATLAS) is both functional and aesthetically pleasing. It features 2 mirrored tapered locking nuts that provide evenly distributed clamping pressure across a custom engineered barrel nut with use of a turnbuckle screw. A ratcheting detent further secures the design while providing positive registration during installation. By design, the even pressure of the ATLAS system avoids distortion of the handguard often seen with current applications during installation. All hardware mounting parts are included with the purchase of an ATLAS Handguard. Lightweight By Design M-LOK Handguard Weights: 15" - 9.07 oz Mounting Hardware Weight: 1.9 oz (same across all ATLAS Handguard options) Features: Full top picatinny rail for optional attachments Quick disconnect sling socket at the 3, 6 and 9 o'clock positions Compatible with low profile gas blocks 1.3" Inside diameter 1.5" Outside diameter Compatible with mil-spec AR15 upper receivers and barrels NOT Compatible with M4E1 Enhanced Upper Receivers ATLAS Handguards are compatible with any Mil-Spec AR-15 upper receivers as well. However, they may not be compatible with billet upper receivers due to indexing tabs SPECS Specs Made In America? Yes Platform AR15 Series ATLAS Attachment Type M-LOK Material Machined from 6061-T6 aluminum Actual Handguard Lengths 14.94"Aero Precision rail lengths measure from end to end. This is the point of contact at the receiver to the end of the last picatinny slot at the muzzle. Weight(s) 15" - 9.07 oz Other Mounting Hardware Weight: 1.9 oz