Keep a guide to fishing knots in your pocket or tackle box.  This waterproof plastic, three card set folds out to a 12 inch ruler.  Includes 10 of the most popular fishing knots: Improved Clinch, Palomar Knot, Uni Knot, Surgeon's Knot, Double Uni Knot, Perfection Loop, Dropper Loop, Surgeon's End Loop, Nail Knot and Blood Knot.