See this product page at Dalton Industries for complete information
Metallic Red secondary spring is heavier load rating than the metallic blue (see "components" page for load ratings). For use in 700 Rhino applications for heavier tires 26" and up.
Also used for 660 Rhino when running 28" and larger tires, and used for Grizzly 700 with 28” and larger aggressive mud titres.