Hafele Clip-on Mounting plates - 0, 2 & 4mm version shown. What does the dimension relate to? How do I choose which one is appropriate for the 80220 155 degree Hafele hinges

The dimension relates to the thickness of the mounting plate. Typically the 0mm is used with overlay hinges, with 2mm/4mm being used for inset hinges. For hinge 80220 we would recommend the 0mm mounting plate.