Stone Creek(TM) Hair Stacker. A Hair Stacker is a tool used to smooth out fur (deer, squirrel, etc.) before attaching it to your hook. It&';s extremely useful when used to tie tails, wings or heads of our flies. It&';s as simple as putting the fur to the stacker, gently hitting a tabletop with it a few times and that&';s it. You now have ready to use, nicely smooth out fur.