The Fab Defense Ultimag features an ergonomic design made for enhanced grip and faster magazine change. It is made of durable, light weight polymer and steel with a specialty made floor plate for specialty-made coupling options. Type Detachable Model Ultimag 30R Finish Flat Dark Earth Series Polymer Window Magazine Caliber 5.56x45mm NATO Capacity 30 Material Polymer Brand Fit AR-15 Platform Model Fit AR-15