All you do with a hair stacker is put the hair in it with the cut end down and then pound it on a table of something to make all the cut ends even. The stacker is in 2 parts and when you pull it apart is lets you get to the squared ends easier.

I usually don't need one tying jigs, but with flies I use it more. Normally with jigs I end up cutting the cut end again to square it off anyway.

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