Aero Precision's complete M4E1 upper and lower combination in 16-inch mid-length configuration. The M4E1 lower features an integrated trigger guard and improved bevel geometry, offering the most common entry-level complete Aero build. Type: Rifle Action: Semi-Automatic Caliber: 5.56x45mm NATO Capacity: 30 Year introduced: 2016, USA Weight: 96 oz Overall length: 32.5" Status: Active Intended use: Home Defense, Competition, Patrol, Service