These are SPRiT MX Complex Rate springs, made of high quality stainless steel. Available in 63.5g, 68g, 72g & 78g, each pack comes with 100 springs.
See below information from SPRiT on the different spring weights and force curve graph for different spring types.
SPRiT Complex Rate Spring
Complex rate springs start lighter than normal springs by 5g - 7g until the actuation point.
The force rises by linear rate after the actuation, results in the same bottom out weight as the conventional linear springs. Complex rate force curve is in between linears and progressives.
Force Curve Graph