... and longest lifespan at roughest condition. Drag bits are designed for medium to hard formation and are used in areas that ... fast cutting,many size.Sizes: 3 3/4", 3.7/8", 4", 41/4", 55/8 ", 47/8", 6", 7.3/8", 4.3/4",5.1/8", 5.5 ... /8", 5.7/8", 6.1/4", 6.3/4 ... ", 6.5/8" 7.3/8" 9 ...