Alpha Forged Cavity Back Iron

Forged Irons - The C1 Pro Irons provide the superior feel and sound that comes from the forging process.  Made from soft 1020 low carbon steel and finished off with a handsome nickel-chrome plating, the C1 Pro Irons combine playability and style.
The Double-Forging Process - The manufacturing process of forging forms the iron head by pressing and pounding the steel with a hydraulic pressure press at hot temperatures.  This is a more complicated process from investment casting, where the metal is melted and poured into an iron head mold. Most golf irons are made from casting.  It is a cheaper and faster process, and is easier to introduce perimeter weighting. But the forging process has many benefits.  It is less prone to metallurgical defects that affect casting.  The double-forging of the club in hot temperatures refines the grain structure of the metal to a much more consistent pattern.  Whereas casting introduces bubbles inside the metal structure when it is poured into the mold.  The hot working during forging also imparts high strength and ductility to the club head due to the grain flow oriented in a consistent direction.
A Superior Sound and Feel - The sound and feel of a forged iron can differ greatly from an investment cast iron.  This is due to 2 factors:  1)  The carbon composition of the steel and 2) The density of the metal (remember cast irons will have voids and air bubbles as opposed to the solid forged piece). Feel is subjective and perceived.  Sound can be quantitatively and qualitatively measured.  Hitting the C1 Pro iron sounds smoother and softer than a typical cast iron.  And for some golfers, sound equates to feel.  Experienced golfers who have played many different irons especially appreciate the soft "buttery" feel of the C1 Pro Irons.  

Cavity Backed Perimeter Weighting - The C1 Pro designers pushed as much weight of the iron head towards the perimeter to raise the moment of inertia, or MOI.  High MOI makes the club head less prone to twisting when it strikes the ball away from the center of gravity.  In golfer's speak, the iron is more forgiving on off-center shots thanks to perimeter weighting.

Several design decisions of the C1 Pro were made to promote forgiveness through perimeter weighting - a large head size, thin yet heavy top-line, and a wide sole.  The most effective is the cavity back.  The hollowed-out area in the back of the iron head forces the mass away from the center of gravity, effectively enlarging the sweet spot.