The Rock River Arms LAR-15 IRS (Integrated Rail System) is a factory-built free-float quad-rail AR-15 with a 16-inch barrel and RRA's two-stage trigger. The IRS handguard is RRA's proprietary free-float rail system providing four full Picatinny rails from the receiver to the muzzle. An alternative to Daniel Defense and BCM rail systems at a competitive price with RRA's premium trigger included. Type: Rifle Action: Semi-Automatic Caliber: 5.56 NATO Capacity: 30 Year introduced: 2008, USA Weight: 7.4 oz Overall length: 32" Status: Active Intended use: Tactical, Law Enforcement