The Foundation Series™ is domestically manufactured and establishes a new standard for reliability, durability, and performance for which US Optics™ is renown.The Foundation Series™ line of optics incorporates and improves upon core components that U.S. Optics™ has developed, proven, and popularized in over 29 years. The Foundation Series™ is machined from aircraft grade 6061-T6 aluminum, and features a low profile ER3K elevation knob, capped US#1 windage knob, adjustable integrated parallax and illumination knob, rapid adjustable 180° magnification throw, and customizable options to easily meet the needs of every end-user.Build your foundation with confidence; Build it with U.S. Optics™.