180130 Irwin Industrial Tool Co 8158ZR 3/4 x 10, National Course Thread, Fractional Tap, Carbon Steel, Ideal For Routine Maintenance, Repair Work For Rethreading Where High Accuracy Tolerance Thread Is Not Critical, Straight Flutes Are Ground To Provide Rapid Chip Removal For Efficient Threading, Designed For Hand Threading Work In A Variety Of Materials Taps Produce A Class 2B Thread, Use 21/32 Drill Bit.