Select a leakdown tester assembly for either 10mm, 12mm or 14mm spark plug

To read more about the Dual Gauge Leakdown Tester, including operation instructions, click here.

Choose from 10mm, 12mm and 14mm. This is a measurement of your engine's spark plug thread diameter - not the diameter of the hose. NGK plugs starting with "C" are 10mm. Starting with "D" are 12mm. If you use a brand other than NGK you will have to remove the plug and measure the thread diameter.

This 30" leakdown tester extension hose comes with the proper quick-disconnect fittings assembled.