The most important tool for spinning hair and shaping flies is a vacuum cleaner. The second most important tool is a hair packer. The familiar shape of the Ergo Hair Packer is borrowed from the cork handle of a fly rod. It sits comfortably in hand, and provides enough mass and taper to push against to make sure that your spun hair gets packed as tight as a bowl at a Mongolian Barbecue. There are two different diameters of hole for accomodating flies of different sizes, and the ends are beveled to ensure that hair can be packed deep into the bend of the hook.