SDP/SI is an ISO 9001 manufacturer of over 262 compression spring, constant force spring, Belleville washer, Belleville spring washers, extension springs, Negator constant force spring, spring motors, spring motor assembly, spring posts, power reels, and torsion springs. SDP/SI can modify our standard catalog parts to your spec or produce completely custom components. SDP/SI uses state-of-the-art CNC production facilities. Modified standard catalog parts or custom components are also an option.