As far as I can tell they are only going to have 3 different spring rates available for now. When I go to order them there's only soft/stock/firm. The rates they list for the soft and firm are 3.75/4.45lb and 2.2/2.6lb. Like I've said before, I'm 100% convinced that they are the same the Kyosho SC6/RT6 springs. The clear X rings are identical to Kyosho's as well.