The cone was not spinning when I took it out of the box. It started spinning normally after I applied some force. I unscrewed the ring covering the bearing (by hand, it wasn't tightened) and saw a rubber (or PVC) gasket there. The inside diameter of the stuffing box is 1-2mm larger than the corresponding diameter of the cone :(. So the stuffing box is a fake, it doesn't protect the bearing in any way. The bearing itself works very well but a normal seal will do its job most likely master. Iβ¦