This hub has a 24mm bore, 8mm keyway, 56.0mm OD, and 15.0mm length.
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.. CntrlFlx Cplng Hub w/Key,Single,Bore 24mm,OD56.