I've been looking at the Estes website and it appears that all references to the standard single-stage E9 motors that I KNOW they sold at one point have been removed. All I see is the E9-8 (upper stage) and various E12s in the 24mm size, plus the 29mm E16s.
Have the old E9s simply gone out of production or have they been rebranded as E12s?
Have the old E9s simply gone out of production or have they been rebranded as E12s?