48-20-3954 - DRILL BIT SDS MAX 1X21IN MX4 4 CUTTER CARBIDE CONCRETE REBARSDS MAX 4CT MX4 1 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