Soft and effective, very good, but expensive. The improvement points are as follows. When tightening the center bolt, since the body is easy to rotate, it is hard to install so that it does not twist. The center bolt has a slot for a flathead screwdriver, but I want it to be a hexagon socket. Because the center bolt is too long to get in the way, can not it be a nut? In this case, it is necessary to have anti-rotation pins etc in the main body.