Interesting that the Teric behaves differently than the Perdix. I have 32% and 21% active on my Perdix and switching via Select Gases has the MOD tracking appropriately. I just looked at the my Teric, though, and and with both active the MOD for 32% was 133'. After turning off the 21%, MOD was displayed at 111'. I'm more concerned about the two behaving differently than anything else. Perhaps I haven't had enough coffee yet?