This is the Multi rate Spring Set for the Traxxas 1/16 Shocks used on the Slash, Revo (1/16)

Spring Steel Construction
PROGRESSIVE Springs, PROGRESSIVE-Rate (PRS) allow the optimum spring rate for each application. These multi-rate springs are soft at the beginning to soak up the small bumps, but transitions (crosses over) to the stiff part of the rate to resist bottoming on jumps and other big "hits. "

Two 1.1mm wire Red PROGRESSIVE Rate Springs
Two 1.3mm wire Silver PROGRESSIVE Rate Springs
Two 1.5mm wire Gun Black PROGRESSIVE Rate Springs

Red
length: 25mm
Inner diameter: 11.2mm
Wire diameter:1.12
Silver
length: 22.5mm
Inner diameter: 11.2mm
Wire diameter:1.00
Black
length: 29mm
Inner diameter: 11.2mm
Wire diameter:1.00