I love these! Absolutely necessary for a canvas you're currently working on, so if there are three colors of green you don't confuse them. However, also REALLY helpful way to store/ sort yarn you're using in your own designs. I sometimes work a design from the Elizabeth Bradley books with a more modern, vibrant color way. Plus, before I start a kit I compare the kit yarns to my wool shade book and identify the yarn by color number. Then, if I have yarn leftover from a kit I can store the yarn by it's number. Many kits use same/similar yarns, so this is a really efficient way to store & use yarn. Lastly, this material (Lexan, I think) is very expensive, so even if you have a wonderfully skilled husband like I do, you will be hard pressed to make them for less. In short, a greatly versatile product at a good price. Doesn't get better than this!