It has an 18mm bore, 6mm keyway, 41.3mm OD, and 18.0mm length.
The complete coupling has a balanced design and can accommodate speeds of up to 4,500 RPM. Hardware is metric and tests beyond DIN 912 12. The multiple piece construction allows for a highly customizable coupling that easily combines clamp or set screw hubs with inch, metric, keyed, and keyless bores.