Our most popular series of masonry drill bits is the Standard Heavy Duty Rotary Masonry Drill Bit which is a carbide tipped drill bit. The Standard Heavy Duty Rotary Masonry Drill Bit has a specially designed, slow spiral flute that gives these carbide tipped masonry drill bits exceptional strength and rapid debris removal. The steel used to produce our SM Series rotary masonry drill bits is more resilient and allows for limited flexing. Combined with the special carbide tip, this proven design allows the SM Series masonry drill bits to provide long life at a reasonable cost. Maximum flute length for SM series masonry drill bits:18" long to 48" long, 1/ 4" dia. through 3/ 4 " dia. is 16". All SM Series masonry drill bits larger than 3/ 4" diameter have a maximum standard flute length of 5-1/ 2".