They don't have any type fastener. They would have to be glued to something. I have used them for the focal point on the barefoot sandals that I make. They turned out real good. My 9 years old granddaughter likes to attach them to headbands. Thanks for interest. God Bless.
is this ruler in centimeters...forgive my question, but I really am quite ignorant of these measurements...give me good old USA inches to measure items with anyday...chuckles