The Terra Deluxe Hair Stacker is a must have for tying hair bodied flies. Tying Elk Hair Caddis, Stimulators, or Comparaduns? You will need a hair stacker to even the tips of the hair. When properly stacked, the hair wings on your flies will look full and even. Use a hair stacker with any tailing or winging hair- elk hair, deer hair, squirrel hair, calf hair, moose, etc.