CTA Tools 98141 Pro-Thread 14mm Spark Plug Repair Kit, Tapered Seat Allows You to Repair Tapered Seat and Gasketed Spark Plug Ports For Use on Aluminum and Cast Iron Heads Kit Includes a Tap, Installation Tool and 3 Inserts Heavy-Duty Construction Ensures Durability Insert Sizes:1/4-Inch, 3/8-Inch and 5/8-Inch