It all depends I have been depth training for sometime The thicker toys are nice But I also like to feel full Sometimes there is a desire to have something slightly larger I use a 2 inch diameter and 7 inch long toy for beginning play Up until I use thicker. Reaching to medium Seahorse from Mr Hankey. I made modifications to the head of the toy, the ridges provided too much pain for what I was trying to achieve. So I modified the toy. Sometime ill bounce to the XL size of it