“The fit is perfect on the pi 4b, and it will even fix the pi 3a if you cut off the one fin so it can fit round the camera slot. As I brought 6 for the pi 4bs, and one for my pi 3a which was getting hot. It does the job of helping cooling down, even more now I've added 2 fans to each heat sink so it had side cooling blowing across the top and downward draft.
Perfect”
