Astro Pneumatic Radiator Test Cap (Late Model Audi, VW, Porsche) No. 23 7858523The Astro Pneumatic Radiator Test Cap (Late Model Audi, VW, Porsche) No. 23 7858523 allows easy testing for leakage in radiator system and quick change of coolant. Unit is suitable for late model Audi, Volkswagen & Porsche vehicles. The Astro Pneumatic Radiator Test Cap (Late Model Audi, VW, Porsche) No. 23 7858523 works with the 78585 Astro Pneumatic Universal Radiator Pressure Tester & Vacuum Type Cooling System Kit.