These are very old koto bridges. There are 13 of them, all the same height, but two have a slightly lighter, brownish-red color. The material is unknown, but the part where the strings rest and the back appear to be made of some kind of natural material (bone)? However, I am not an expert, so I am not sure. There is a chipped part on the white material attached to the back. If you like old things, please use them. Stored at home for many years. They will be arranged flat, secured, and shipped in an A4 size package.