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: 33gMaterial: Aluminum AlloyConnection Diameter: 10mm to 10mm/0.39 inch to 0.39 inchTotal Length: 30mm /1.18 inchOutside Diameter : 25mm /0.98 inch Package Content:1 x Shaft coupling