TAKE ALL OF THE GUESSWORK AND CLUMSY CHARTS OUT OF DRILLING HOLES FOR TAPPING. WITH THIS SET ALL YOU NEED IS THE FINE METAL CASE TO QUICKLY SEE THE CORRECT DRILL FOR THE TAP YOU NEED. 6-40 TAP WITH #33 DRILL 8-36 TAP WITH #29 DRILL 10-24 TAP WITH #25 DRILL 10-32 TAP WITH #21 DRILL 1/4-28 TAP WITH #3 DRILL 5/16-24 TAP WITH LETTER I DRILL 3/8-24 WITH LETTER Q DRILL 7/16-20 TAP WITH 25/64 DRILL 1/2-20 WITH 29/64 DRILL METAL CASE CONVENIANCE AND QUALITY AT AN UNBELIEVABLE LOW PRICE!!!!