SDP/SI - Stock Drive Products/Sterling Instrument is a U.S.-based manufacturer of power transmission and motion control products, serving customers since 1950. The company specializes in precision gears, high-quality mechanical components, gearboxes, and the assembly of both mechanical and electromechanical subassemblies. SDP/SI is part of the Designatronics family of brands, offering a wide range of stock mechanical component options and customized solutions to meet diverse engineering needs.