One of the best quality hairs out there for fly tying. The SDH from Nature's Spirit is a shop favorite for tying deer hair head flies. This product is hollow and allows for a good amount of flair, but it's not so intense that it become bulbous as deer belly will. As well, you maintain the "natural" markings of the deer hair so it gives the head of the fly a little texture rather than one vibrant color.
Overall, this product will forever be at our tying benches because I haven't found a deer hair with this sort of consistent quality ever before!