Perfect Fit Diesel Compression Test Adapt Adapter uses with STAR Diesel Compression Tester TU-15. Compatible with GM: Duramax 6.6L Turbo Diesel (2005-present). Also works on a Duramax LML engine. Perfect Design M10-1.25 thread adapter with quick disconnect screws into the head of the engine in the glow plug hole. Manufactured to specific thread tolerance standards. Superior Material Diesel Compression Tester Adapter is made of high quality steel and copper. Features high strength, anti-corrosion, anti-burst. Suitable for use in wet or dry environments. Reliable use, offer the quality, reliability, and durability you expect and save your charge. .