Zero backlash. One-piece metallic spring coupling. For little torque shaft connect.Absorption of parallel, angular misalignments and shaft end-play by spring action.Widely used in drive systems for encoders, instrumentation,lead screws, small pumps, feed rollers and anywhere light to medium duty, torsionally flexible coupling is required. Specification:Color: Silver ToneMaterial: Aluminum alloyConnection Diameter: 12mm to 10mm Total Length: 30mm /1.2 inchOutside Diameter : 25mm /0.98 inch Package Content:2 x Shaft coupling