XRAY item 308288 - 4S Spring Set C=2.8 2 T4 2017 Specs (300023) T4 Series
Linear 4S springs marked 2.8. The 4S springs are specifically created to check the SLP shocks and they're 20mm long. Wide range of 2.
The 4S springs, much like virtually any XRAY springs, are manually determined, chosen, and matched into pairs to ensure exactly equal size and damping traits.