After many hours of use, the brushes occasionally do need to be replaced on your High Velocity Dryer. Most groomers and stylists go for years without changing the brushes. If arcing, sparking are evident, then the brushes may need to be replaced. These Brushes are compatible with the K-9 Series of dryers, Kool Dryer, EDEMCO F2002 Dryer, EZ- DRY and most other dryers. These Brushes are compatible with any AMETEK 115923 Motor