The Ford Spark Plug Repair Kit is designed to air in repairing Ford Modular Cylinder heads. This is a high quality foolproof way to repair the damaged spark plug threads in a fast and permanent manner. No need to remove the heads to get at the threads in need of repair. Patented insert fits perfectly into engine to insure a permanent repair with no loss of compression. Comes with a guide system in insure straight drilling and tapping of cylinder. Works on the 4.6L, 5.4L, & 6.8L V10 Ford Triton engines. Kit includes (8) alloy steel inserts. Please watch the enclosed DVD for comprehensive instructions on proper use of this product.