Proto Concept Irons C01


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A new-generation muscleback iron crafted
with revolutionary development through integrated forging
with pure titanium inside

This muscleback incorporates an outstanding 25 g of titanium inside through forging with a round rod.
While maintaining the beautiful muscleback figure, extra weight is distributed to the periphery to attain the same forgiveness of a cavity back iron.

PROTO-CONCEPT’s flagship model takes advantage of the feel and maneuverability that are the greatest advantages of musclebacks while providing forgiveness.

The world’s only integrated soft iron forging pure titanium inside

Titanium is embedded in the soft iron at the round bar material stage and forged as a single piece of soft iron with built-in titanium. This method is extremely special and difficult to emulate, as it requires proper placement of pure titanium in the clubhead without compromising the thickness of the face.

Of all the irons on the market, the C01 iron is currently the only iron made with this single forging technology using soft iron and titanium.

Pursuit of high functionality that goes beyond the concept of musclebacks

By using special technology that combines 25g of pure titanium into a single head, mis-hit forgiveness and head size providing sense of security were both attained while maintaining the muscleback shape.

The extra weight of titanium, which has about half the specific gravity of soft iron, is distributed to the periphery of the face to achieve a face size equivalent to a soft iron cavity back and a deep center of gravity despite being a muscleback.

Craftsmanship leveraged to attain superior feel and sound

Built-in pure titanium has its setbacks in that hits will feel harder. In addition, titanium is not included in irons 8 to PW, which creates differences in feel.

To solve this problem, the soft S20C material is used for irons #5 to #7 in which titanium is built in, and the hard S25C material is used for irons #8 to PW. By using different soft iron materials with different hardness, consistent sound and feel across the irons were pursued.

The thickness of the face of the soft iron area is secured while titanium is built in, providing the superior feel of soft iron forged musclebacks sought by professionals and advanced players.


  • C01 FORGED
  • Conventional ironwith soft iron forging
  • Structuring

    An outstanding 25g of pure titanium is built into the S20C soft iron forged head (#5 to #7). The use of titanium with light specific gravity allows weight to be distributed to the periphery, resulting in a larger face size for a muscleback and a deeper center of gravity.

  • Structuring with only soft iron material used.
    Performance is determined by shape and wall thickness

  • Manufacturing method

    Forged in one piece using pure titanium with S20C soft iron round bar inside. The titanium with different hardness and characteristics is integrally molded with placement and thickness as designed.

  • Forged iron sample

    Forged head designed to be larger
    are polished by hand to shape

  • Features

    With pure titanium that has about half the specific gravity of soft iron built into the head, the weight is distributed around the periphery of the head to provide the forgiveness of a cavity iron while having the thick feel of a muscleback with the unity of metal.

    The thickness of the soft iron section behind the hitting point is well secured while providing the feel of a muscleback.
    The soft S20C material is used for irons #5 to #7 in which titanium is built in, and the hard S25C material is used for irons #8 to PW in which titanium is not used. By using different soft iron materials with different hardness, consistent sound and feel across the irons were pursued.

  • It is made of a single material, soft iron, and has an attractive feel. However, the performance is not much different from musclebacks of the past.

The integrated forging process of titanium and soft iron rods creates unprecedented performance.

The idea of combining titanium with soft iron forged irons has been around for more than a quarter of a century. Models with titanium built into the head were introduced in the 2000s, but with less satisfying feel and performance.

The soft iron integrated forging process with pure titanium of the C01 iron incorporates 25g of pure titanium into a soft iron round bar and is forged three times to maintain a sense of unity as a club and to achieve forgiveness by taking advantage of the light specific gravity of pure titanium.
The use of an advanced manufacturing method that allows the position and thickness of the titanium inside the head to be arranged as designed while integrally forging with soft iron has resulted in a revolutionary muscleback iron that will leave history as a golf club.

Clubhead structure Muscleback with titanium inside oft iron-forged undercutting
Pocket cavity Pocket cavity
Size/Sole Compact/Sharp
Slightly Compact/Standard
Standard/Slightly Wide
Slightly Large/Wide
Material S20C Soft Iron + Pure Titanium (#5-7)
S25C Soft Iron (#8-PW)
S25C Soft Iron + CNC Undercutting (#5-7)
S25C Soft Iron (#8-PW)
SAE8655 Chromium Molybdenum Steel
S25C Soft Iron
SAE8655 Chromium Molybdenum Steel
S20C Soft Iron
Loft angle (7I) 32° 32° 32° 31°
Features A muscleback with titanium inside crafted through forging together with titanium and soft iron round rod A tour cavity crafted with precise forging using soft iron only and CNC undercutting A tour pocket cavity engineered with deep and low center of gravity and face with high-strength thickness deviation A pocket cavity with excellent maneuverability that also prioritizes forgiveness


Number #5 #6 #7 #8 #9 PW
Loft(°) 25 28 32 36 40 45
Lie(°) 60.5 61 61.5 62 62.5 63
Bounce(°) 3 4 5 6 7 8
FP(mm) 4 4.1 4.1 4.3 4.5 4.8
Carbon steel(S20C)Forged #5~#7 / Inner Titanium
Carbon steel(S25C)Forged #8~PW
Satin Finish / Mirror finish on back of face

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