GIGIClean Collars for 14-Ounce Wax Warmers, 20 Pieces

What are these made of? Are they reusable?

Does it really work?

I was concerned it will catch fire, it’s made out of paper, right??

I have the mini which takes the 5 oz. cans of wax. Do you know if the 14, 8 and 5 oz. cans have the same diameter?