Sub 70 built its reputation on a simple pitch: tour-quality clubs at direct-to-consumer prices, shipped from Sycamore, Illinois instead of marked up through a retail chain. The 639 MB is the purest expression of that idea. It's a forged muscle back blade that costs roughly half of what a comparable Titleist or Mizuno set runs, and it doesn't apologize for being exactly what it looks like.
This is a compact head with a thin topline, minimal offset, and a full muscle pad behind the sweet spot. Forged from soft carbon steel, it delivers the dense, quiet feel at impact that blade players buy blades for. There's no hidden tungsten, no undercut cavity, no face insert. Miss the center and you'll know immediately, which for the right golfer is the whole point.
The honest question with the 639 MB was never whether a small company could forge a good blade. It was whether the club could hang with the legacy names at a fraction of the price. By most accounts from the golfers who actually gamed them, it can. Sub 70 also lets you order single heads and mixed sets, so plenty of players pair these short irons with the more forgiving 639 CB in the long irons.
요약하면
The Sub 70 639 MB (2021) is a compact blade for skilled ball-strikers who want feel and shot control.
Sub 70 639 MB 아이언: 주요 스펙
- 카테고리
- 블레이드
- 모델 연도
- 2021
Sub 70 639 MB: the iron lineage
The 639 MB is the 1st of 2 generations Sub 70 has released in this line, from the 639 MB (2021) to the 669 MB (2025). It is where the line started. The 669 MB (2025) replaced it.
- 2021639 MBYou are here
- 2025669 MB
로프트 스펙
Stock steel shaft. Lofts are approximate and subject to manufacturing tolerances.
About the Sub 70 639 MB
The 639 MB follows classic muscle back architecture: a concentration of mass directly behind the impact area, a shallow blade length, and a leading edge that sits close to square with very little offset. That geometry rewards golfers who deliver the club consistently and want to flight the ball in both directions. Workability is the design priority, and the compact profile makes it easy to open or shut the face without the head fighting you. Where Sub 70 diverges from the big brands is the business model, not the metallurgy. The forging is soft carbon steel with a satin or black finish option, and because you buy direct, custom lie, loft, shaft, and grip adjustments come standard rather than as an upcharge ordeal. The 2021 version kept the clean, badge-free back that made the original popular with traditionalists.
Who Should Play the Sub 70 639 MB?
- ✓Low single-digit handicaps who strike the center of the face consistently and want full control over trajectory and shot shape.
- ✓Blade-curious players who want to try a forged muscle back without committing $1,400 to find out they hate it.
- ✓Combo set builders pairing MB short irons with cavity back long irons, since Sub 70 sells individual heads.
- ✓Traditionalists who want a thin topline, minimal offset, and a clean back with no badges or paint fill shouting at them at address.
자주 묻는 질문
Are Sub 70 639 MB irons forged or cast?
They're forged from soft carbon steel. Feel at impact is dense and quiet, comparable to established forged blades from the major manufacturers, which surprises a lot of people given the price.
How forgiving is the 639 MB?
It isn't, and it doesn't try to be. This is a true muscle back with a compact head and mass centered behind the sweet spot. Off-center strikes lose ball speed and give you honest feedback through your hands. If you want help on mishits, look at the 639 CB or Sub 70's game improvement lines instead.
How does the 639 MB compare to blades from Titleist or Mizuno?
Head shape, offset, and feel are in the same neighborhood as clubs like the Titleist MB or Mizuno MP-series blades. The real difference is price. Sub 70 sells direct, so a full set costs roughly half of what the legacy brands charge, with custom fitting options included in the base price.
Can I mix 639 MB irons with the 639 CB in a combo set?
Yes, and it's one of the most common ways golfers order them. Sub 70 sells heads individually, so a typical build runs 639 CB in the 4 through 7 irons and 639 MB in the 8 iron through pitching wedge. The profiles blend cleanly at address.
What shafts can you get in the 639 MB?
Sub 70 offers a wide custom menu direct from the factory, including common steel options like the KBS Tour and Dynamic Gold families, at no upcharge for most choices. You pick shaft, flex, lie, loft, and grip at checkout rather than paying a fitter to reshaft later.
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