Thanks!
Scott they have a lot of different kinds and styles, but basically they have a handle and then some rotate and some don't. They all some way clamp down on the hackle so you can hold it as you make the wraps.
Go to FOAL and look at fly tying and then click on beginners and look about half way done and you will see woolly worm and something else. Click on that and it explains what you do and has several ways to Palmer hackle.
Or even easier look at this link and just scroll and go through the pages of hackle pliers. If you get to a point you want to buy some I would say talk to me or someone else that has tried several as they are not all equal for sure.
Bob Marriott's Fly Fishing Store - Product Catalog - Hackle Pliers

