I thought I had done a ton of research prior to buying the set of RBZ irons I got, apparently I didn't realize that the 4 and 5 irons are designed very different from the 6-AW. Here's a comparison between the two different designs: The 4 and 5 have a much thicker head and the bottom of the club is much thicker ... almost like a funky hybrid iron ... I hit the normal irons great but when i pick up the 4 or the 5 the club literally opens up in my hand when I hit the ball, I can feel it move with both clubs more often than not. Anyone ever heard of problems like this with the RBZ long irons?