The ATLAS R-ONE is the newest addition to the Aero Precision Handguard lineup. Machined from 6061-T6 Aluminum, the R-ONE line of handguards are designed with size and weight in mind, providing the perfect handguard for your lightweight build. 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.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