For VW For Golf 1999-2005 (MK4) 1.8T 20V engines. For VW For GTI 1999-2005 (MK4) 1.8T 20V engines. For VW For Jetta & Jetta GLI 1999-2005 (MK4) 1.8T 20V engines. It compensates for the 14mm height difference between the two coil types, ensuring a secure fit and proper seal with the valve cover.