Most of the reviews are for a different product “Soap Nuts”.
I did find one review, 4 stars that said they put essential oils on them and then throw them in the dryer, noting one started fraying after 2 months (but wondering if it was due to the essential oils).
Having said that,
Dryer sheets are horrible for the environment, and these are a wonderful way to replace them.
I have a set of 3 dryer balls I bought earlier this year from the mothership, for about this same price. Work fine on sheets, towels, etc., but they don’t prevent static cling on my permanent press stuff.
I just ordered a pack of 6 wool balls (felted New Zealand wool) for the dryer yesterday from Amazon for $7.49. Sure sounds better than two for $9.99.
No, I’ve never tried any wool balls before, but I’m tired of dryer sheets.
After you posted this, I realized I actually bought the set of 6 dryer balls, probably this same set. I just use 3 at a time, haven’t used the other 3 yet. And as I said previously, I do get static cling on things like tricot nightgowns, etc.