Yeah, just the big spring.
See, from the feedback of some members, I decided to remove a coil from the large springs, along with making the top diameter smaller.
While making the top diameter smaller was a good idea for broader compatibility, what I forgot to think about during my calculations was that removing one coil while having a smaller top meant that more force had to be applied for compression, and since removing a coil meant more force per coil was being applied, well…
The spring deformation went from 0,9mm right down to 2,8mm, which was not very good.
The 25% improvement in conductivity was nice, but not worth that large deformation.
So, I took a lot more time on my hands to find a new way to improve the spring, which was hard and time consuming, but lead to these developments:
1. Could change the material to BeCu C17500 45% IACS. Was not going to happen for obvious reasons, being that mechanical properties are quite important.
2. Could change the material to BeCu C17550 60% IACS. However, cost would explode to stratosphere levels.
3. Finally, after a lot of research, and myself getting a new job, I found that electroplating a thick copper layer(20-25um) would result in the same performance boost of 20-25% of the large spring, but while preserving the goal of having good mechanical properties.
And that goal was met, and the improvement is actually even better than I intially predicted, since the conductivity boost of the 3rd Gen springs are applied to both sizes of springs.
TLDR: The 3rd Gen springs are a large overall improvement over all previous generations of springs.