Back in September, Callaway unveiled its new Apex irons, which it bills as ''forged performance'' clubs. Now comes the Apex Pro edition, a tuned-up version for better players.
The Apex Pro clubs have a one-piece, 1020 carbon steel, forged construction designed specifically to deliver a soft and responsive feel – that is also a primary goal of the standard Apex clubs. The Apex Pro heads are more compact than the standard Apex clubs, and have less offset, a thinner topline, a narrower sole, and a shorter blade length from heel to toe.
One of the standout features on the Apex Pro irons is what Callaway calls its High Performance Wide Groove profile. Callaway engineers discovered that tour players and better amateurs were often generating too much spin out of the rough, largely because of high clubhead speed, reducing both distance and consistency. To remedy this, they came up with a new wide-spaced groove.
GOLF BUZZ: Callaway unveils Apex 'forged performance' irons 
In addition, the Apex Pro clubface is about 17 percent thinner than the 2013 edition of the X Forged irons, which improves ball speed. Increasing ball speed was secondary to improving sound and feel on the Apex Pros, and to that end Callaway added a high-damping polymer insert in the back of the head that helps eliminate unwanted vibrations at impact.
The soles of the long irons (2-5) have tungsten inserts to lower the Center of Gravity, which produces a higher launch angle and makes easier to hit. The Center of Gravity gets progressively higher down the set from longer to shorter irons. In the 9-iron and pitching wedge, this higher CG helps flight the ball down a bit and deliver a flatter trajectory.
The stock shaft on the Apex Pro irons is the new KBS Tour V, which Callaway describes as a premium, mid-launch, low-torque steel shaft that maximizes energy transfer for a smooth feel and faster ball speeds. A graphite UST Recoil shaft will be available through custom order.
The Apex Pro irons will be available at retail in early January. Callaway hasn't yet announced a suggested retail price.
Here is a video from Callaway talking about the new Apex Pro irons: