Quickly test backpressure and clogged or obstructed catalytic converters. Three stage adapter has12MM & 18MM thread sizes to fit most domestic and import vehicles oxygen sensor ports. The standard 1/4”-20 tip provides the ability to test through the exhaust pipe when O2 sensor ports are Inaccessible.* High temperature silicon hose prevents damage to tester from high exhaust temperatures.Kit Contents: 0-15 PSI gauge 6” High temp silicone tube 3 Stage adapter Flange adapter Blo-molded carrying case!