There are many implant sizes available. There are also different implant shapes available, such as round and a lozenge, or oval configuration. The largest size commonly available is 555cc. Having said this, the feel is not like that of a breast implant, it is much firmer. They are definitely palpable. However, I prefer fat for several reasons. It feels natural. It is your own tissue. I can spread the tissue over a much larger distribution and really contour the buttock. Finally, even on a slender patient I can usually get at least 400cc per buttock. My average fat injection is 600-700cc per buttock. Finally, and more importantly, a fat injection recontours your ENTIRE waist hips area to give you a curvy silhouette, rather than just a bigger butt.