This product is a Genuine Shimano replacement part, designed for use with Ultegra and GRX RD-R8000, RD-R8050, RD-RX800, RD-RX805, and RD-RX812 rear derailleurs. For a complete exploded diagram of all spare parts, please refer to www.si.shimano.com. Available in black and silver, this derailleur spare is offered in one size.