Designed to be used on oxygen sensors on modern vehicles with a cut out on socket enables socket to fit over wiring harnesses. Thread chasers are: M12 x 1.25 M18 x 1.5mm 3/8 Drive: Straight 80mm deep 22mm offset 31mm high 22mm 1/2 drive: Offset 50mm high 22mm Completing this thread chaser set is a durable alloy steel manufacture.