SDS MAX 4CT MX4™ 11/8 X 16 X 21 Our MX4™ 4Cutter SDS MAX 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. We designed our MX4™ 4Cutter bits with sharp centering tips for exact spot drilling in concrete. The integrated 4cutter design prevents lockup in rebar reducing downtime. Optimized flutes remove dust faster reducing heat and delivering up to 15% 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™ 4Cutter Drill Bits are ideal for concrete with rebar and masonry applications.