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 ToneNet Weight: 18gMaterial: Aluminum AlloyConnection Diameter: 6mm to 8mm/0.24 inch to 0.31 inchTotal Length: 25mm /0.98 inchOutside Diameter : 20mm /0.79 inch Package Content:1 x Shaft coupling