Replacement brush heads specifically for the PRO SONIC-X sonic toothbrush, sold in a set of 2. The bristles are made of nylon and are soft. * Model Name: PRO SONIC-X * Type: Replacement brush heads * Compatible Models: PRO SONIC X * Materials: ABS resin, bristles: nylon * Bristle Hardness: Soft * Quantity: 2 brush heads * Heat Resistance: 50 degrees Celsius I am selling these because I accidentally purchased the wrong ones. They are new and unopened. Thank you for looking.