... Drag bit are manufactured from forged high quality alloy steel and premium tungsten carbide insert, plus state of art welding technology ... Drag bits are designed for medium to hard formation and are used in areas that contain a lot of rock ... oil field. longer life and fast cutting,many size.Sizes: 3 3/4", 3.7/8", 4", 41/4", 55/8 ", 47/ ... 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 ...