The three-layer construction of the metal coil spring component enables high torque transmission to be achieved in a compact form factor.A type that uses SUM24L-equivalent material as the hub material and piano wire for the coil spring (the MM-K type) and a type that uses stainless steel for the hub and coil spring to boost corrosion resistance (the MM-K-S type) are available. Select the type suited to your usage environment.