5/16" x 18, National Course, Self Aligning Tap & Drill Set, Performance Threading System Self Aligns Tap In Pre Drilled Hole Especially In Irregular Surfaces Or Through Holes, Carbon Steel, Ideal For Routine Maintenance, Repair Work & For Rethreading, Straight Flutes Are Ground To Provide Rapid Chip Removal For Efficient Threading, Designed For Hand Threading Work In A Variety Of Materials, Includes Letter F Drill Bit.
