SC8UU Linear Bearing With Flex Element For M4

I've reduced the mounting hole diameter to 3.2mm, so it is tight enouph for threading to work with the stock M4 screws.

I'm using one as lower bearing on my Anet A8 B X-axis and it works like a charme!

Story behind:
The Y-axis of the Anet A8 has only 3 bearing, that works but imo 4 bearings are a lot better, so I needed at least one more bearing. However, the ball bearings are working better on Y-axis cause they are more tolerant, so I used one from the X-axis for that.
First I've tested