Differential cylinder pressure tester for the Rotax/Jabiru (12 mm spark plugs) and other aircraft engines (18mm spark plugs). Now you can conveniently check your engines condition, its compression (ie cracked rings sticking or damaged valves) and its leakdown rate against its built-in calibrated standard to determine your engine's cylinder leakage. Factory calibrated precision gauges matched to within +/-2%. Includes Spark Plug Adapter, 24" pressure hose, and complete instructions. Protective form-fitted hard case included.