M12x1.25x15mm spark plug insert p/n 42123 QTY 5 M12x.125x15mm spark plug inserts by Time-Sert QTY 5 Requires kit 4212 search # B00RW4PZHK to install this insert. Common reach for M12x1.25 spark plugs. professional spark plug repair inserts by Time-Sert Quanity 5 pcs.