They say this is for small dogs, unfortunately, the "bone" is about an inch thick, which makes it a little hard for my small dog (pug, and a larger pug at that) to get his mouth around it and benefit from the brushes. The brushes are recessed, with only a quarter inch or so sticking out from the plastic casing. The thing that really got to me about this product though, is that it did not come with doggy toothpaste. You'd think it would, since they show it in the picture, but nope, had to order that separately. My dog shows absolutely no interest in this thing now, maybe he will once I get the toothpaste.