This is a pack of 250 sets of parts for backpin button making. They're compatible with most american made machines that make 1 inch backpin buttons. Each set has 4 components: Metallic Shells, Metal rings collets, copper backpins and plastic mylars measuring 1 5/16 inch diameter. Each component is packed in separate plastic bags for your convenience. If you have any questions about this product, feel free to contact Upick Deals, seller of this product.