Features 1、Firm Connection: The coupling can connect two shafts with different diameters or one motor shaft for firm and stable connection. 2、Efficient Works: Fix the bearing and sprocket tightly on the shaft and reduce the stress when shafts are not in good alignment. 3、Extensive Using: Allows for wide application on blowers, 3D printers, DIY robots, CNC machine tools, stepping motors and more. 4、Perfect Fitting: Suits perfectly for NEMA 17 step stepper motor, the coupler connector has 14mm diameter as well as 25mm length. 5、Including 10Pcs: Made from premium aluminium alloy material, all the 10pcs enable very convenient replacement and installation. Specification Item Type: Shaft Coupling Product Size: Approx. 25 x 14mm / 0.98 x 0.55in (L x D) Application: Applicable to 3D printers, motor couplings, ship models, aircraft models, car models, engraving machines, etc. Product Adaptive Motor: 42 Stepper Motor Shaft Locking Mode: Screw fixed type. Package List 10 x Shaft Coupling