This hub has a 11mm bore, 4mm keyway, 25.0mm OD, and 9.5mm length.
The use of a keyway prevents the coupling from slipping on the shaft if over torqued. This keyed clamp style single insert type hub requires the user to mate it with one other hub and one acetal insert. Ruland supplied Controlflex couplings are a lightweight, low inertia, and zero-backlash coupling designed for use in encoders, tachometers, resolvers, and light duty power transmission applications. It is compact and can fit in smaller envelopes than equivalent single beam or double insert Controlflex styles.