1Firm Connection: The coupling can connect two shafts with different diameters or one motor shaft for firm and stable connection. 2Efficient Works: Fix the bearing and sprocket tightly on the shaft and reduce the stress when shafts are not in good alignment. 3Extensive Using: Allows for wide application on blowers, 3D printers, DIY robots, CNC machine tools, stepping motors and more. 4Perfect Fitting: Suits perfectly for NEMA 17 step stepper motor, the coupler connector has 14mm diameter as well as 25mm length. 5Including 10Pcs: Made from premium aluminium alloy material, all the 10pcs enable very convenient replacement and installation.10 xShaft CouplingItem Type: Shaft CouplingProduct 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 MotorShaft Locking Mode: Screw fixed type.