Powerbuilt 648421 14MM Spart Plug Thread Repair Kit Rethreads damaged 14 millimeter spark plug holes in aluminum heads Includes tap and 4 inserts: two 7/16", one 5/8" and one 13/16" Meets or exceeds ANSI standards. Lifetime warranty. Rethreads damaged 14 millimeter spark plug holes in aluminum heads Includes tap and 4 inserts Inserts reach: two 7/16 inch, one 5/8 inch and one 13/16 inch