It's a head. For your head.
Will you have double head power when you use this wacky hat? Probably not, but this version of the 'plush head hat' (of which there are many) adds a new level of silliness which is small Sonic arms that grow out of the bottom of the head, and velcro together under the chin to make the hat literally hold onto your head.
The spikes are plush/stuffed, as is the face, to give it some shape independent of any head inside. The Sonic rendition here is classic, with black eyes & normal smile. The ears actually do stand up, and the face proportion is actually pretty ok for such a sort of odd item. This is supposed to be on Amazon somewhere, but what company made it? It is sure one of the wackier Sonic merchandise items out there, but it is good for a laugh when you see it.