Artificial Sinew Bobbin
Perfect size to toss in your saddlebags or camp sewing kit. Strong and easy to use, especially with a glovers needle for sewing leather. Also, great where improvising is necessary, hmmm, repairing canvas in a pinch when you can't seem to find your cotton string and the wind has made a sail out of your tent, now there is a hole and it's raining. Yep, been there, used sinew.
60 feet of artificial sinew. Can be used whole or split into several strands for finer threading.