Well to my mind the only true rotary vise out there where you can spin the fly is the Nor-Vise. With the Nor-Vise you can spin the fly with a flip of your fingers and wind thread on the fly in a hurry. With other rotary vises there is too much mass to spin the fly using this technique. You can use other rotary vises to wind on tinsel or wire by holding the material and rotating the vise. This makes it very easy to place the material exactly where you want it. It is very handy to wrap hackle. You tie in the hackle and then rotate the vice holding the hackle. This gives a very presice hackel wrap. It is quick to unwrap and re-wrap until you get the hackel just right. All of this can be done with a non-rotary vise but not as quickly or as easily.