"Trace the racing line with the nimble GF210. The maximum potential can be achieved when used in conjunction with Sustec Damper. Sporty and stylish, GF210 lowers a vehicle 1 1/4-1 1/2in (30-40mm) while rasing the spring rate 20-30% over stock"

when they say "rasing the spring rate 20-30% over stock" what does that mean?
i might get a set of these used for a few months. what do you think.