The brushes that were sent with the Waterpik has the smaller heads. At first, I thought I would miss the bigger size, which are also available. But, I feel I have more control over the corners in my mouth with the smaller heads that were included with the package. Happy with them.
My wife and I shared a Waterpik Sonic Fusion for several years. We sold our home and moved into a Senior Living Center with 2 bedrooms & 2 small baths, which we share. She got the Waterpik, I got a battery powered toothbrush (no comparison). I had some complex dental work done recently and the Dentist told me I should get a Waterpik flosser to make sure my new dental work was clean. Oh boy!! I can get my own now. I got the waterpik Sonic Fusion 2.0 Pro and it works great. We are mid-80's and im sure these will last longer than we will. Our kids may even argue over who gets the Waterpiks when we pass.