I bought a set of six dryer balls, and I use them with a bit of essential oil each time. They impart a nice light scent to my laundry. I actually purchased them so that I could wash down-filled items and haven't needed to do that yet, but based on use in my regular laundry, I am confident that they will work better -- and quieter -- than the tennis balls I have used in the past. I highly recommend the set of six, especially if you love earth tones. Each one I received is a different natural wool color, and they are so pretty that I keep them in a bowl in my den between uses.