What is this? It is a shaft fitting accessories to connect two different shafts and make them rotate together to transmit torque. Applied for RC model car, RC model boat, 3D printers, snow blowers, grinders and other DIY projects.What will I get?Color: Silver ToneMaterial: 45# SteelSurface Finish: ElectroplatedSection: OneSize: 52mm x 20mm/2.05inch x 0.79inch (L*D)12mm to 12mm(0.47inch to 0.47inch)Package Contents: 1 x Joints, 1 x Wrench, M5*0.8 Fastening ScrewsIs there any advantages of the product?Made of 45# steel and with electroplated finish, the joint is sturdy and durable.Features with large transmission torque, high efficiency, stable transmission, small gap impact. Especially under the correct technical control conditions, it can access long lasting use.