Ruland MJC15-4-A is a zero-backlash jaw coupling hub with a 4mm bore, 15.0mm OD, and 7.6mm length. It is a component in a three-piece design consisiting of two aluminium hubs and an elastomeric insert called the spider creating a lightweight low inertia coupling capable of speeds up to 8,000 RPM. This three-piece design allows for a highly customizable coupling that easily combines clamp or set screw hubs with inch, metric, keyed, and keyless bores. Spiders are available in three durometers allowing the user to tailor the performance of the coupling to their application. Ruland jaw couplings have a balanced design for reduced vibration at high speeds. Hardware is metric.MJC15-4-A is machined from bar stock that is sourced exclusively from North American mills. It is manufactured in our Marlborough, MA factory under strict controls using proprietary processes.