Provides consistent accuracy through better production methods. Electro-discharge machined from 4140 steel, heat-treated to Rc 38-40, then vacuum tempered to help retain these tolerances for many years to come. One-piece blade is cut from solid steel barstock, so it won't fly apart when your shot matters most. Consistent, click-adjustable detents for windage and elevation give precise repeatability. All models except Accro feature a full-serrated, square corner blade for better target recognition and a rebated square notch for improved, "shadowless" front sight definition. BM #1 Deep Notch features a .020" deeper sight notch and finer surface serrations than st Mfg: Kensight Mfg