I use a lingerie bag to wash them.
After reading several reviews stating the buttons fall off, I decided to use a lingerie bag to wash the headbands, and I have not had a problem after over a month of use.  I love the variety of colors, and I appreciate that they save my ears, because before wearing headbands on a regular basis I was getting scabs behind my ears due to wearing a mask all day.
Rating: 5 stars