From TOFT UK:
A pair of interchangeable press-studs for use with TOFT natural colored alpaca pom poms. Simply sew one half to your hat and the other to your pom pom, then you can mix and match your pom pom color to suit your outfit and mood! It's also useful for removing the pom poms and washing your hat. These also work interchangeably with TOFT colorful pom poms which come with a pre-sewn stud.