Each pin is roughly 20MM in diameter . Our pins are coated with GLASS crystle to give them a very nice shine. Even though sealed, we still advise against exposing it to a heavy amount of water. They will do fine in the rain. Note: These are not pin back buttons. Our pins are much more durable. Our pins are handcrafted using very sturdy alloy and they are so lightweight that you will forget that you even have them on. You can pin our pins on your shirt, jacket, backpack, handbag, or whatever other object you choose. This is a very versatile piece that will look great with many things.