Kit contains the necessary sizes to test compression most gas enginesSnowmobiles, motorcycles, outboards, lawn equipment and much moreIncludes: 10mm x 1.0, 12mm x 1.25, 18mm x 1.5 and the special 16mm x 1.5 Ford adapterFits our compression tester W80579 and others with a 14mm x 1.25 male threadRubber O-rings insure a positive seal and accurate readings The Performance Tool W80577 Compression Tester Spark Plug Adapters Set is the perfect tool for testing the compression of your gas engines, including snowmobiles, motorcycles, outboards, and lawn equipment. This comprehensive kit includes multiple adapters such as 10mm x 1.0, 12mm x 1.25, 18mm x 1.5, and the special 16mm x 1.5 Ford adapter, ensuring compatibility with a wide range of engines. The rubber o-rings in these adapters provide a positive seal, allowing for accurate compression readings every time. Made with high-quality materials, this set is durable and designed to last, providing reliable performance for all your compression testing needs.