These replaceable toothbush heads that I purchased with my Waterpik Sonic-Fusion SF-01W020-1 product I find is so very easy to use but yet powerful. The overall size of these replaceable heads is the absolute perfect size for helping to get into those hard-to-reach areas and so they're built-in floss.
I had a electronic toothbrush, and my dentist told me that it wasn't doing a good job in the back of my mouth. So I purchased this one. I brush first, then use the flosser. I keep pressure at 3. I think the flosser gets at all the nooks and crannies that I wasn't reaching. My teeth even feel cleaner when I finish.