The mad geniuses at Sharp Bros. have created another precision crafted, artistically designed masterpiece, the Overthrow. An open mag well helmet design, with battle-worn dents, sword gashes, and crack lines. Leave it anodized black or give it a Spartan flare ... the customization opportunities with this one are endless. Stand out and strike fear with this terrifyingly awesome receiver set! Features: Machined top to bottom from 7075-T6 aluminum, a peak-strength corrosion-resistant aluminum alloy A hard coat anodize finish per MIL-A-8625, the anodizing model for most military and aerospace products Full compatibility with all mil-spec internal parts Full compatibility with all other aftermarket mil-spec upper receivers Full compatibility with GI standard issue magazines as well as PMags Multi-caliber mark