Regarding this project Connection diameter: 8mm to 8mm, total length: 22mm/0.87 inch, outer diameter: 14mm/0.55 inch Widely used in blowers, 3D printers, DIY robots, CNC machine tools, stepper motors, etc. Similar to rigid clamp couplings, shaft couplings are used to tightly secure bearings and sprockets to shafts and are used in motor and gearbox components. Top fastening type rigid coupling with 2/4 screws for tightly fixing the shaft; High torque, rigidity, low inertia, and excellent sensitivity. Note: Rigid types generally do not allow eccentricity and must be fully adjusted during use. The single piece fixed screw clamping design makes it easy to place items on the shaft and control the holding capacity of the coupling.