Genuine deer sinew. This is backstrap sinew which is part of the muscle fibers found along the back. Sinew is the original thread. These strips can be split into virtually every size and is a must for the traditionalist. Use it for sewing leather, beadwork, featherwork… just about everything. To prepare, break the fibers up into the desired width, moisten, and roll on your leg in one direction (not back and forth).You just made natural thread! Just be sure not to do this in shorts if you have hairy legs. Ouch!