The Cobra King F9 Speedback irons look a little more rigid than previous game-improvement irons from the company.
While flow in a design is a subjective concept, there are straight lines in the F9s where you'd expect there to be curves. And that's not just to look different than the competition, but it's rooted in building an iron with high moment of inertia (MOI) and plenty of high-launching distance -- a compromise the company says this class of irons has needed to make in the past.
The Speedback functions in the irons are technically different than the driver and fairway woods in the King F9 line, but the idea is the same: maintain high MOI, a low-and-back center of gravity and deliver on distance game-improvement iron players need. Speedback in the irons is a strip of steel wrapped just above the contact area on the sole designed to add mass and move the center of gravity low and back.
The shaping of the Speedback spreads weight out toward the heel and toe regions, while a combined 33 grams of tungsten were added to the heel and toe of the 4-7 irons. Cobra says the tungsten increase MOI by 10 percent.
The E9 variable-thickness PWR Shell face is 3 grams lighter than the F8s and has 1.8 mm pockets in the upper heel and toe regions to expand the sweet spot. The PWE Shell insert has an undercut sole design with a 1.2 mm internal Speed Channel designed to flex and return energy to the ball at impact.
The face is CNC-milled for tighter tolerances in lofts, groove shaping and face friction. Groove shapes differ throughout the set, with V grooves in the 4-7 irons to reduce spin and U grooves in the other irons for more control. The gap and sand wedges sport tighter groove spacing.
The hosel lengths get progressively shorter toward the long irons to lower center of gravity for higher launch, while the higher-lofted clubs have longer hosel lengths to raise the CG closer to where ideal impact is made.
The F9 co-molded medallion has three pieces: aluminium, TPU and an acrylic foam designed to improve feed and sound.
Cobra Connect is included in the set, and golfers who purchase a set (minimum six pieces) will receive screw-in Arccos sensors or Cobra Connect grips to use for the other clubs in their bag, including putter.
The King F9 Speedback irons are available in traditional length and One Length (7-iron lie, loft and weighting) options for $800 in steel with a stock KBS Tour 90 (R, S) shaft or $900 with a stock Fujikura Atmos 60 graphite shaft (L, R, S). The stock makeup in steel is 5-PW, while it's 5H, 6I-PW, GW in graphite. The women's F9 Speedback set is $900 in graphite with 5-6H, 7I-PW and SW with the Fujikura Atmos 55 shaft in ladies flex.