SPRiT MX Complex springs follow a exponential force curve up until actuation, and then switch to linear until bottom out. They are within 0.5% deviation as of October 2020.
There is no polarity on complex springs. As SPRiT says:
"According to the Newtonians, force of object A on B = the opposite force of object B on A. It damn doesn't matter which end. You feel the pressure exactly by the pressure you press"
Each bag contains ~100 springs.
Further descriptions can be found on SPRiT's website.