Whitey says: This is an easy FG Knot tool to assist in tying an FG knot. The Knot assist tool tightens the tension on one end of the leader so it is easy to tie an FG knot without the knot slipping. Made in Japan from a carbon material to help reduce the weight and ease of use. Able to be used from PE0.3 – PE6 and leader sizes from 3lb – 70lb.