Proto-Concept C01 Irons Specifications
Full factory loft, lie and length chart for the Proto-Concept C01 irons, 2020–2023.
- Years produced
- 2020–2023
- Category
- Blade / Muscleback
- Construction
- forged one-piece muscle back with forged-in titanium rod (5-7 irons)
- Material
- S20C carbon steel with inner titanium (#5-#7), S25C carbon steel (#8-PW)
- Set makeup
- 5–PW
Loft, lie & length chart
| Club | Loft (°) | Lie (°) | Length (in) | Bounce |
|---|---|---|---|---|
| 5 | 25 | 60.5 | 38 | 3 |
| 6 | 28 | 61 | 37.5 | 4 |
| 7 | 32 | 61.5 | 37 | 5 |
| 8 | 36 | 62 | 36.5 | 6 |
| 9 | 40 | 62.5 | 36 | 7 |
| PW | 45 | 63 | 35.5 | 8 |
Lofts and lies are the factory standard build. Individual clubs may differ if they have been bent, re-shafted or re-gripped during their life.
About the Proto-Concept C01
The C01 was the muscle back in PROTOCONCEPT's original C-series - the premium Japanese brand established in 2019 as a collaboration between the Endo forging house and the Golf Partner retail group, with its first irons reaching the market in 2020. Its signature technology is a roughly 25-gram pure titanium round rod impregnated into the S20C billet before forging in the 5- through 7-irons; the titanium is about half the weight of the steel it displaces, deepening the centre of gravity to give the blade profile something closer to cavity-back launch, while the 8-iron to pitching wedge are conventional S25C forgings. Heads are sold component-style, 5-PW, and assembled to order in Japan or the USA. Lengths below are the manufacturer's recommended steel assembly lengths; PROTOCONCEPT publishes face progression rather than offset, so that key is omitted. The C01 TBic, which replaced the titanium rod with an inner ceramic, superseded it in July 2023.
Related models
Frequently asked questions
What is the loft of a Proto-Concept C01 7-iron?
The Proto-Concept C01 7-iron has a loft of 32 degrees, with a 61.5-degree lie and a 37-inch recommended steel length.
What is special about the Proto-Concept C01?
The 5-, 6- and 7-irons are forged with a pure titanium round rod inside the S20C billet - roughly 25 grams of titanium that deepens the centre of gravity. At the time it was the only iron on the market with titanium forged inside the head.
Who makes Proto-Concept clubs?
PROTOCONCEPT is a Tokyo-based premium brand created in 2019 by the Endo forging house together with the Golf Partner retail group; heads are forged to Endo's spec and clubs are assembled to order in Japan or the USA.
Finding a used set
The Proto-Concept C01 ran from 2020 to 2023 and is no longer in production, so the used market is the only source. Search eBay, 2nd Swing, Golf Avenue and the PGA Tour Superstore trade-in listings, and check the loft and lie against the chart above before buying — sets this age have often been bent from standard.
- protoconceptgolf.com C01 product page (archived 29 November 2022) — manufacturer spec table used here: lofts 25/28/32/36/40/45, lies 60.5-63, bounce 3-8, FP 4-4.8 mm, S20C forged #5-#7 with inner titanium and S25C forged #8-PW, satin finish, plus recommended-assembly steel lengths 38 to 35.5 inches (common to all listed steel shafts)
- shop.torquegolf.com Proto Concept C01 listing — independent corroboration of the full loft/lie/bounce/FP chart and the 25 g forged-in titanium rod
- mygolfspy.com / mygolfspy.jp 'Know Your Japanese Brands: Proto Concept' (September 2021) — brand established 2019, Endo x Golf Partner collaboration, titanium roughly 50% lighter than the displaced steel; C-series irons including the C05/C07 on the market from 2020. Japanese gear databases register the C01 in 2021, so the 2020 dating carries some uncertainty
- mygolfspy.com 'First Look: Proto Concept C01 TBic' (July 2023) — the inner-ceramic C01 TB replaced the first-generation C01, dating year_discontinued
Last reviewed 2026-07-29. Spot an error? [email protected]