The M3 irons have a progressive cavity design with thin toplines; a thinner cavity in the long irons to increase ball speeds, but a thicker blade in the short irons for more control and workability in the scoring clubs.
Mass is moved to the heel and toe areas in the long irons, boosting MOI for more forgiveness; but the short irons are more uniform in size across the blade.
The 8620 carbon steel clubheads have a matte black PVD finish. Stock shafts are the Aldila RIP Phenom 95 and Dynamic Gold XP steel. The MAP for 4-GW sets will be $899.99 with graphite shafts or $799.99 with steel shafts.
And as a reminder, all the Wilson Staff FG Tour M3 clubs hit retail in January 2014. More info can be found on WilsonStaff.com as the product launch draws near.