These bearings are suitable when precision is not required. As you can see from the photos, the left one is of good quality, the right one is not very accurate at all. .15 provides a very loose fit on precision shafts. External dimensions are ok. The bearings are very sticky, but that's normal, a little alcohol won't fix that. They are a bit difficult to turn but I think that means they are well lubricated in my opinion. Hope that helps. OUT