SPRiT  MX  Complex Rate Springs      
 
...  Curved inbetween Progressives and Linears
 
-  World Premier 99% precisionMar 20,  2020
-  Challenging to 99.5% precision - avrg 0.3g variance since Oct 2020 
-  Made in Korea of super-precision premium materials under SPRiT control
 
-   Complex Rate v4.3  =  Progressive + Linear  
 
I have designed these Complex rate springs to be much lighter than the conventional linear springs by 5g - 7g, but heavier than Progressive springs by 3g - 4g until the actuation point with progressive rate curve as Graph 1.   
The force rises by linear rate after the actuation, results in the same bottom out weight as the conventional linear springs.  
Complex rate springs are hard to find any example in the electronics industry, the production is trickier and quite complicated.
  
* No Polarity on Complex springs. 
  According to the Newtonians,   Fab  =  - Fba  
  
   You can say this simply, "When you press the lighter end, the heavier end will be pressed by exactly the same pressure. vise versa."   or 
   "It damn doesn't matter, which end.  You feel the pressure exactly by the pressure you press." 
   
Please Enjoy Your Premier Builds, 
SPRiT 
 
  
Bottom out Force  /  Force ratio Before vs After actuation
 
63.5 C  -  Starts at 28g,  actuates at 43g.  Force ratio  =  3 : 4   
 
68 C     -  Starts at 31g,  actuates at 47g.  Force ratio  =  3 : 4   
 
72 C     -  Starts at 33g,  actuates at 50g.  Force ratio  =  3 : 4 
 
78 C     -  Starts at 35g,  actuates at 53g.  Force ratio  =  3 : 4
 
  
For further info  >   spritdesigns.com/mx