They are meant to replace fabric softener sheets, and liquids and also claim to reduce drying time by 25% for large loads to 30-40% for small loads. I had several skeins of 100% wool yarn, so I decided to make some for myself to try relatively cost free.
I used Brown Sheep Lambs Pride Bulky in my stash. I had about half a skein which made five 2 1/2″ balls.
All I did was wind each ball by hand, place them in a large sock separating each ball with a rubber band, and wash them in hot water on a heavy duty cycle, then throw them in a nice hot dryer, and they felted beautifully. (I should note that, when winding each ball, I used a crochet hook to pull the yarn ends into the center of the ball before I felted them.)
They do reduce drying time somewhat, and are nice to have when you just need to throw one item in the dryer to remove wrinkles but I can’t tell that they soften my clothes all that much. Still I keep mine in my dryer, which can be somewhat of a challenge sometimes, as there are four of us in my family, who do laundry, and not everyone is careful about keeping them out of just dried clothes and in the dryer. So often, I go searching…..I have heard that you can add a few drops of essential oil to these to make your laundry smell nice. I haven’t tried it, though.