Approximately 1.2cm in diameter. This is a set of 5 back buttons. (These are changing buttons for school uniforms, with a black plastic base and the words "CHANGING BUTTON" on them, used to fasten the buttons from the back.) Replacing the back buttons is easy, even for children. The 5 back buttons will be placed in a pouch and sent via Japan Post's mini-letter service with simple packaging. There is no tracking number. Delivery will be by mail slot, not hand delivery. Items for which payment is confirmed by 12:00 PM (noon) will be shipped the same day. (There are basically no days when we cannot ship, but if there is an urgent matter that prevents shipping, we will ship the next day.) Depending on your region, delivery usually takes 1-3 days after the shipping date, and will be delivered to your mailbox. For details, please check the estimated delivery time from Osaka using the mini-letter service on the internet. * Brand new. * Free shipping.