Extremely versatile the Cottarelli T-REx Vise is very well used by those who makes fly tying a true religion.
It's long and perfectly shaped fork allows you to use two different heads at the same time giving you the chance to have your hooks totally blocked.... no matter how big they are.
It  magically becomes a regular vise once you decide to use a single head to tie your regular size patterns.
Amazing stuff from Cottarelli!!