We bought this set with the Bissell Crosswave Pet Pro 230 because we use it so often! These parts will likely need to be cleaned frequently by the machine. Brushes are used for mopping floors and are more likely to come into contact with puppy accidents, so it's good to have extra supplies so they can be washed and dried while another brush is used. The filter is in the area where dirty water collects and can filter out solids like dog food. We had an elderly dog who became ill for almost a year before eventually dying and for a time we used the Pet Pro almost daily. We now have a new dog who is adjusting to his new home so expect some accidents. We love how the Pet Pro works so much that we use it to clean our kitchen floor even when there is no dirt on it.