Um, unusual buttons. These are for repairing jeans, jackets, bags, etc., but you can also use them for making accessories or as studs. They're convenient to have around. I bought them to repair the buttons on my jeans pockets. I ended up with a lot left over because there were so many in a set (´・ω・`;) The back is a screw. You make a hole in the part you want to attach it to, big enough for the male screw part to go through, and then tighten it with pliers. Since it's a screw, you can also remove it. *There is no screwdriver slot on the male side. Please use pliers or something similar instead of a screwdriver. Pattern: Crown Size: Diameter: Approximately 1.7cm Thickness when attached: Approximately 1.8cm Quantity: 5 sets