This is the most advanced yet simple AR lower receiver ever made! - We designed this lower receiver out of necessity and a desire to have a true ambidextrous AR-15 M4 platform. Allowing it to accommodate any and all shooters without the need to add countless costly add-ons. Whether you are a right or left handed shooter or forced to shoot with your off hand the STT-15 has you covered! STT-15 is designed specifically for situations in which there's no room for error and you must use your rifle to take that shot! - We machine the STT-15 directly from a billet of 7075-T651 aerospace grade American aluminum on our brand new Haas CNC machinery. This allows us to hold ultra-tight tolerances and make sure that the final product is exactly as designed. The finished receiver is then finished in Mil-Spec MIL-A-8625 Type III hard anodizing. - Even though this is a tool to some it is a show stopper to others! The final finish is every bit as important as the features and materials the lower consist of! The STT-15 is everything you have come to expect from a San Tan Tactical and then some. The STT-15 is your final answer in the AR M4 firearms platform!