This 21 inch nylon floor scrubbing brush fits the , which has a spin-on/spin-off design for easy changing. The CT230 uses 2 of these brushes to have a 42" cleaning path. The brush is sold individually, so be sure to order 2 when needed. The brush has nylon bristles that are durable and can be used on any type of floor. Nylon has the longest lifespan and recovers its original form very easily. If your brush becomes deformed from storage, or heavy scrubbing, simply run it under hot water for 5 - 10 minutes and the nylon will recover its original form.