Filled with water... *Sigh* Although it will/can last longer in a more suitable temperature than other sex toys. That thing slips on ya, something sharp pricks it, or you happen to cum and collapse over it.
POP....plus their FAQ are less convincing will only last a few uses. Like their electrical shock hazard joke though. Better off with a Fleshlight and will not cost $80 unless you pick the ones with the new textures.