Ursprünglicher Beitrag von: mayer ,
The difference is in the size of the circle on the inside of the foot. The ones with the smaller circle go into newer machines like the McBook Airs. The main problem with installation is lining up the pin because you are doing it blindly. I stick the foot on the edge of a pocket knife, use a strong light on top and one coming in from the side. After getting the foot correctly in place I put a little super glue on the pin and around the circular opening as the sticky stuff on the replacement feet is not as good as the original.