I purchased this item in the hopes of helping myself and my son to be better knot tiers. These little cards do a great job at educating in the art of the knot. The cards are thick plastic and should last a lifetime. If you are looking for a minimal tool to help boost your knot tying skills, a product which is long lasting, and for relatively cheap. Check this one out.
Disclaimer: Any activity involving rope can be dangerous and may even be life threatening! Knot illustrations contained in this web site are not intended for rock climbing instruction. Many knots are not suitable for the risks involved in climbing. Seek professional instruction. Many of these knots have histories of use tracing back hundreds of years. However, many critical factors in their use today cannot be controlled, including: the appropriateness of knots used in particular applications, the age, size, and condition of ropes (knots weaken the rated breaking strength of rope anywhere from 50% to as much as 80%, even more in the case of old and worn rope); and the accuracy with which these descriptions have been followed. No responsibility is accepted for incidents arising from the use of this material.