I'm not sure what they mean either. I was at a demo day last week and hit a whole bunch of irons - mostly for fun. One thing I like to do besides hitting "normal" shots is try to hit big sweeping hooks and fades, just to check workability and what not. Once again, not big surprises. I could hit just as big a hook or fade with Callaway X-20's as I could with Titliest AP-2' or Mizuno MP-57's. Again, for me, it has everything to do with how open or closed my clubface is and maybe deviating just a bit either inside-out or outside-in depending on what shot I'm trying to pull off. For me, club-face size makes no difference.