Instruction: Extract information from the supporting document to answer the given question.

Input:
Question: What is it made out of?  I can't find the material information anywhere.
Document: My son has eczema so I can't use fabric softener at all. The preservatives in them causes him to break out in a really bad rash, so I decided to eliminate fabric softener from all of our clothes so I didn't have to wash more loads and waste resources.I think these work great. It makes our clothes softer, fluffy, less wrinkly, and I find it does reduce static on my synthetic material clothes. This is a great alternative if you can not use fabric softener.
The dryers balls cut time off our drying time and made the clothes fluffier. I did not find them to be cheap or poorly constructed at all. Would have been a 5 star if I didnt find them cheaper at Target.
There are lots of poorly-designed or poorly-made dryer balls out there that can be useless or worse. This isn't one of them. It's made of sturdy yet pliable material that keeps items in the dryer from bunching up together, but it's not so heavy that it bangs loudly inside the dryer when it's running.
These items might otherwise cling to the sides, which would elongate drying time and set wrinkles, but with the balls, they keep tumbling and dry more quickly.I used to use tennis balls in the dryer, but find these balls more effective because of the projections, which are smooth and don't hurt clothes at all. Even though I like the balls and will rebuy when the ones I have wear out, I can't give them five stars because they don't replace fabric softener.
Expensive and not worth the higher price. It was not made very well. I found much less expensive packages that did the same job and had same quality for alot less.
No static and no more dryer sheets! I save money on dryer sheets and they soften my clothes without breaking down the fibers of the material like dryer sheets frequently do.
These are o.k., but they really aren't a substitute for the standard laundry additives. I have used these with softener sheets. I say "used" because after a month or so these fatigued. They are cheaply made and probably not worth bothering with.
This purchase was a request from my daughter, both her and I haveused these for a long time and find that they not only fluff up theclothes but also helps prevent wrinkles.
Have used a few years unable to find in grocery stores now. Allergy to soap and softners was panic till checked on Amazon. Only thing able to use for a softner that I don't break out and itch like crazy.
I bought these balls to dry the clothes of my baby because I did not want to use chemicals. They are not what I expected. They are hard, made of plastic. and very lightweight (they get soft after 20 min in the dryer but this is it. They also need to have some weight to soften the clothes)and do not do their job at all. Actually, I do not see any difference between drying clothes with or without them.
Answer: They are made out of what is called a thermal plastic rubber. Giving it the ability to retain high heat without melting!