Very good watch! It is 33 millimeters if I'm not mistaken and it seems like a very good size, also not too thick on the side, it is compact and convenient. We got it for our 9-year-old and he has been wearing it for a few days now, even in the sea, and it still looks brand new. He takes good care of it and doesn't wear it in the shower because I read in the instructions that water with pressure is not allowed, so we wash it under the faucet with low water pressure after being in the sea each time. I have no complaints!
The only thing I could say is that the design is somewhat odd and we don't know why the number 3 is missing... But we couldn't find any orange watch with all the numbers, a bit strange :/ in the end, it still works fine and tells the time correctly, it just takes a few extra seconds for him to think about where the numbers should be, it's a habit.
Overall, it seems perfect, especially for the little one and as a gift for a child or an adult for casual activities like sports, swimming, etc. We have other watches from the same company and we are satisfied, just BE CAREFUL when changing the battery to make sure the membrane is properly in place because water might get in (mine got damaged that way). I recommend it without a second thought!