Originally Posted by smerdyakov
The tongue stiffener is a piece of plastic that sits between the tongue and the laces. In my experience the stiffening was noticeable. i preferred to leave them out. The boots are pretty stiff to begin with. At least last season's were. I was told that many people add the tongue stiffeners after the boots start to loosen up a bit. I hope this helps.
This was my experience as well