Amabur A300-100 Grinding Wheels Polishing Head 3mm Shank 100-Pieces

Received the Amabur A300-100 Grinding Wheels Polishing Head 3mm Shank 100-Pieces today and immediately tried to put them to use.Although the heads are a good size for my application, they are not balanced at all - I had to dress them before I could use them. Will not purchase these again.