Thanks for your suggestions, richwawr. Yes, I'd like to alter the symbology, not the geometry. My symbols are asymmetrical, so I can't just rotate, I have to horizontally flip. Like with a symbol of a flag with a flagpole, I'd like to be able to have the flagpole face either the left side or the right side. Worst case, I could create two different symbols, as you said, but that would double the set of symbols I have to maintain (which I'd like to avoid if at all possible).