Oval cross-section wire die springs are made from oval cross-section wire and subdivided in four series.
Each has a different load and deflection but same dimensions. Each series has its own color which allows easy identification.

Tolerances
Spring rate: +/- 10%
Free length:  +/- 1% with a minimum of +/- 1mm
External diameter: the external diameter of the spring is always smaller than the housing diameter indicated in the catalogue
Internal diameter: the internal diameter of the spring is always greater than the diameter of the guiding pin indicated in the catalogue