Powerbuilt 940379 Oxygen Sensor Thread Chaser For cleaning and possibly repairing damaged threads in oxygen sensor bores. Also can be used on M18 x 1.5 spark plug bores Must use anti-seize when using this product Meets or exceeds ANSI standards. Lifetime warranty. Use with 3/4 inch hex socket or 3/8 inch square drive Size is M18 x 1.5 oxygen sensor Works on M18 x 1.5 spark plug threads