If it helps, with the Affinity and Evoke, the RXL and RL have ti rails, while the R has steel rails.
Originally I think there were at least 2 different versions of the Inform, in terms of the amount of padding. So there might have been a difference in rails, too.
- Gray 2010 carbon WSD road bike, Rivet Independence saddle
- Red hardtail 26" aluminum mountain bike, Bontrager Evoke WSD saddle
- Royal blue 2018 aluminum gravel bike, Rivet Pearl saddle
Gone but not forgotten:
- Silver 2003 aluminum road bike
- Two awesome worn out Juliana saddles