16 mm Petrol Compression Tester Adapter by OTC®. Use with OTC compression testers (or other compression testers with a 14 mm thread) to access hard to reach spark plug holes. Easy-to-turn feature makes starting thread fast. Triton is a Registered Trade Mark of the Ford Motor Co. Compression Tester Ford Adapter. This product is made of high-quality materials to serve you for years to come. Designed using state-of-the-art technology and with customers in mind. It will meet your needs and deliver great quality at an affordable cost.