San Tan's STT-15 Billet Lower features an ambidextrous design for your AR-15\M4 platform, which allows it to accommodate any and all shooters without the need to add countless costly add-ons. It is directly from a billet of 7075-T651 aerospace grade American aluminum and holds ultra-tight tolerances. The finished receiver is then finished in Mil-Spec, MIL-A-8625 Type III hard anodizing. The STT-15 is everything you have come to expect from a San Tan Tactical, and then some.