The TX Series of shaft couplers from R+W America LP, Bensenville, Ill. (rw-america.com), are made of glass-reinforced thermoplastic instead of the more-traditional metal. This reduces the coupler's mass, moment of inertia, and cost. The backlash-free units are designed as drop-in replacements for traditional servo insert couplings. They handle torque from 2 to 660 Nm (18 to 5,840 lb-in.), and bore diameters of 8 to 45 mm (0.375 to 1.75 in.).