The design differs between the inside and outside of the circular buttons, making them elegant and stylish. Large buttons: Diameter 2.3mm, Thickness 2mm, 8 pieces Small buttons: Diameter 1.8mm, Thickness slightly less than 2mm, 2 pieces I believe they are made of plastic. The color may be difficult to discern in the photos, so please check them. If you are concerned, please refrain from purchasing. I hope someone will like them. Thank you.