High Quality Brass MaterialThese 5 metal fittings are made of pure brass, which is strong and wear-resistant, not easily damaged, rusted and corroded, and can be used for a long time. The clutches are dimensioned very precisely, with brushed and polished surfaces, perfectly matched to your different machines. Brass Shaft SetOne clutch set is available in five different sizes, 2mm-2mm, 3mm-4mm, 4mm-4mm, and 5mm-5mm, including all commonly used product sizes in the market to meet your needs. different needs in different scenarios. Connection FunctionThe function of brass coupling is to connect two shafts (master and slave) in different mechanisms so that they rotate together and transmit torque to improve the dynamic performance of the shaft system. When starting the engine, it can be used to reduce the starting force and improve the machine. Easy to HandleThe brass coupling can connect two optical shafts of different diameters, a motor and an optical shaft, or shafts of different diameters. You can use it with our awesome screws and gadgets to ensure easy installation without outside help. Wide Range of ApplicationsThis brass fitting is widely used for blowers, 3D printers, DIY robots, CNC machines, stepper motors, etc. Designed to be similar to rigid clamp couplings, the coupling is used to securely attach bearings and sprockets to shafts and for engine and transmission components. Features: The entire clutch body is made of high-quality brass, hard and durable, not only beautiful but also durable. The surface is treated with a special oxidation treatment that resists light, oxidation and corrosion. Shafts of different diameters can be connected and the bearings and pinion are securely attached to the shaft. The most commonly used couplings are manufactured according to the International Leyland standard, which is widely used for model shaft connections. Specification: Material: Brass Size: Length: 20mm/0.79inch Cross Section Diameter: 9mm/0.35inch Side Hole Size: 3mm Color: Gold Quantity: 5 Pieces Package Included: 5 * Copper Fittings. 20 * Screw 1 * Hex Key Notification: 1. Due to manual measurements, please allow 1 - 2mm error. I hope you understand. 2. The color of the items displayed on the screen may vary slightly on the screen.