Diameter: approximately 2.5cm Hole diameter: approximately 0.8cm Thickness: approximately 0.2-0.3cm These are Dutch beer bottle gaskets, reportedly used as strap locks by Queen guitarist Brian May. They're becoming hard to find these days, so if you've been looking for them, don't miss this opportunity! I've added a picture of them attached to a ukulele. The strap pin diameter is about 1.3cm, and they fit without any problems. If you'd like a set of 4, please contact me via the comments section, and I'll list them for 1,299 yen. I removed and washed these from a bottle I drank recently. However, how they feel may vary from person to person, so I would appreciate it if those who can confirm the condition of the product from the images, don't mind minor details, and understand that these are items stored at home would consider purchasing. If you would like to see more detailed images, please request them. If these don't sell at this price, I plan to use them myself. Please refrain from price negotiations other than for combined shipping. I plan to package them with cardboard and ship them via regular mail. Please understand that I will be using recycled materials. I am also selling rare tableware (Royal Copenhagen, Wedgwood, Noritake, Narumi, etc.), delicious food items, and Hotman towels. Please take a look! I offer a discount on shipping for those who wish to combine items.