So, I personally prefer using concave type bearings, because it helps with tilt and horizontal play. And as much as I love side effect yoyos I can’t say I prefer them. The reason being, is that it is very difficult for me to tune SE yoyos with anything other than the OD 10 ball bearing. I absolutely love the idea, but I just can’t get them smooth without that 10 ball bearing. Has anyone had this problem? I have been told it is because the OD 10 ball is very smooth, but I want input on this problem I am having.