I received these springs today - they are metal with sharp edges and horribly dangerous looking! I would never think of giving something like this to my cat, she would probably scratch herself or poke herself in the eye. And even if I somehow was crazy enough to think these were a good idea, I couldn't give her one anyway because they came all mangled and entwined together. What an awful purchase! Amazon should be ashamed doing business with a seller like this who is purposely trying to cheat people out of money or worse, harm their cats!