#14 x 20, National Special Thread, Machine Screw 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 Drill Bit 13/64″.