These are great for what they are meant for. They are strong and not easily damaged at all. They are great for strength building and for PT use. I have no complaints about them.
A second unexpected use for them is that they make awesome teething rings for a baby. My son discovered one of the set and of course went straight for his mouth with it. Turns out it's better for teething than any of the actual teething toys we own! It has helped soothe his sore gums tremendously and I never expected that use out of this item. I love how great they work for the intended use and the surprise bonus use!