Approximately 1.1cm in diameter. This is a set of 5 back buttons (change buttons for securing the back of student uniform buttons, with a black plastic base and a cherry blossom mark). 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 in simple packaging. There is no tracking number, so tracking is not possible. (We also offer a separate listing that ships via Yu-Packet Post Mini, which does provide tracking.) Delivery will be by postal drop-off, 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 is usually within 1-3 days after the shipping date, delivered to your mailbox. Please check the estimated delivery times from Osaka for Mini Letters on the internet for more details. *New product. *Free shipping.