The Milwaukee MX4? 4-Cutter SDS PLUS Rotary Hammer Drill Bits with solid head carbide deliver up to 5x longer life in concrete with rebar. Engineered with rebar guards to provide maximum durability in hard aggregate and rebar. Milwaukee designed our MX4? 4-Cutter bits with sharp centering tips for exact spot drilling in concrete and metal decking. 4-cutter design prevents lock-up in rebar, reducing downtime. Variable flutes remove dust faster, reducing heat and delivering up to 20% more holes per battery charge. The wear mark indicator on each drill bit shows you when they no longer meet the ANSI requirement. These MILWAUKEE? MX4? 4-Cutter Drill Bits are ideal for concrete with rebar and masonry applications.