It's a Philips Sonicare - which was the first electric toothbrush I'd ever tried. Because I had no other experience, I thought it was basically the same as most other electric toothbrushes... but I was wrong. This brush was 1) very heavy, 2) big to hold, and 3) hard to clean. Where I live, we have very hard water, so each time I used the brush, I would need to unscrew the head, which had some mechanics in it, and rinse and dry it separately. If I didn't, water would get inside, form calcium deposits, grime and whatever else, making it nasty. Also, the handle fit into a charging base where water/grime could also collect. Eventually it quit charging so I explored some other options.
Here's my new one.
It's an AquaSonic. From the pictures online where I ordered it, it appeared to be about the same size as my Sonicare. Boy was I wrong. This brush has a much smaller diameter, it weighs about half of what my old one did, and it's super easy to keep clean. The designers of this brush were really thinking about the users. (Another perk is it has several different settings.) As far as cleaning, this head simply pops straight off, I can wipe it down and pop it back on - there's nowhere for water to collect. It also sets on a peg to charge, which means there is nowhere for water/grime to form.
I'm really enjoying my new AquaSonic brush, and can really see how the difference in design makes a difference to me, the user.