When a design calls for either torsional stiffness or minimum windup, Helical can design a double- or triple-start precision spring. These springs are designed for long travel compression loads. Spring ends, which can be machined to any configuration, were squared to mate with the plate braced against them. Note: A DS prefix in a basic model number denotes a double start (two separate coils wrapped within each other); a TS prefix denotes a triple start.