ZVH1224 Features: * Reference table * Essential tap drill and decimal equivalents reference table for toolmakers, machinists and mechanics * Front has machine screw size tap drill chart for recommended 75pct depth thread * Back has decimal equivalents table in 64ths from 0.02"" to 0.98"" * For national fine and national coarse, American standard pipe and metric threads * Convenient 6"" rule is graduated in 64ths