The Timney Triggers IMPACTARST is designed to provide a sharp, seamless 3-pound break, fitting perfectly into every Mil-Spec AR. All elements are securely held within a lightweight aluminum alloy housing. The hammer is wire-EDM machined from S7 tool steel-characterized by its hardness that resists wear, and superior impact resistance that stands up to heavy use without causing chipping or breaking. Other parts are EDM cut from A2 tool steel, then subjected to heat treatment to Rc 56-60, ensuring a prolonged service life. The original hammer/trigger pins from your rifle are sufficient for installation; the unique design by Timney effectively prevents pin walkout.