John most of the larger suppliers will have it. The thread doesn’t follow the normal 3/0, 6/0, 8/0 sizing. When you order the thread you will see numbers like GSP 50, GSP 75, GSP 100, and GSP 200. The number refers to the number of stands in the thread. The higher the number, the stronger and thicker the thread. For me the 76 or 100 is plenty strong enough to spin the deer hair for the head on these flies.