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Sub 70 built its whole business on selling forged irons direct to your door for a fraction of what the big brands charge, and the 669 MB is the purest expression of that idea. This is a muscleback blade, full stop. Compact head, thin topline, almost no offset, and a sole that begs for clean turf interaction. If you play blades, you already know whether this is for you.
The 669 MB replaces and refines what Sub 70 was doing with earlier better-player irons. It's forged from soft carbon steel, so the feel at impact is that dense, buttery thud good players chase. There's no cavity, no tungsten, no forgiveness tech hiding behind the badge. What you get is a small sweet spot, honest feedback, and the ability to move the ball exactly where your hands tell it to go.
Here's the honest part. Sub 70 prices this blade around $105 to $120 per club, which is roughly half of what a comparable forged muscleback from Mizuno, Titleist, or Srixon runs. The steel is good, the shaping is legit, and the shafts and grips are name-brand at no upcharge. You give up a big-name headcover and pro shop bragging rights. That's the trade.
In short
The Sub 70 669 MB (2025) is a compact blade for skilled ball-strikers who want feel and shot control. The set runs 4-iron to PW with a 32° 7-iron.
Value sweet spot
About a year old, so the first real discounts have landed while a replacement is still 6 to 18 months out. Strong value without feeling dated.
Based on release timing and this line's typical refresh cycle, not a live price quote.
The 669 MB is the 2nd of 2 generations Sub 70 has released in this line, from the 639 MB (2021) to the 669 MB (2025). It followed the 639 MB (2021). It is the newest generation in the line.
| 4i | 5i | 6i | 7i | 8i | 9i | PW |
|---|---|---|---|---|---|---|
| 22.0° | 25.0° | 28.0° | 32.0° | 36.0° | 40.0° | 45.0° |
Stock steel shaft. Lofts are approximate and subject to manufacturing tolerances.
Typical carry by swing speed, adjusted for this set's actual lofts. Your numbers will vary with strike, shaft, and conditions.
| Club | Loft | Moderate swing~135y 7-iron | Average swing~150y 7-iron | Faster swing~164y 7-iron |
|---|---|---|---|---|
| 4-iron | 22° | 160 y | 178 y | 195 y |
| 5-iron | 25° | 152 y | 169 y | 185 y |
| 6-iron | 28° | 144 y | 160 y | 175 y |
| 7-iron | 32° | 135 y | 150 y | 164 y |
| 8-iron | 36° | 125 y | 139 y | 152 y |
| 9-iron | 40° | 115 y | 128 y | 140 y |
| PW | 45° | 106 y | 118 y | 129 y |
Carry distances are modeled from TrackMan-based norms scaled to each club's loft, not measured for this exact model.
The head shape is classic muscleback with a compact blade length, a thin topline, and minimal offset that lets you work shots and see the leading edge sit square behind the ball. The muscle sits low and slightly toward the toe to keep the center of gravity where a blade player wants it, which is directly behind impact for a penetrating, controllable flight. Forging from soft carbon steel does the heavy lifting on feel, giving you the crisp, quiet strike blades are known for and the mishit feedback that tells you exactly where on the face you caught it. The sole is narrow with modest grind relief, so it cuts through turf cleanly for players who take a shallow, ball-first divot. This is a set that rewards a repeatable swing and punishes a lazy one, which is the entire point of a blade.
The Sub 70 669 MB's 7-iron is lofted at 32° - near-traditional - close to the classic 32-34° benchmark. For a golfer with an 85-95 mph swing speed, this projects to a 7-iron carry of approximately 143-153 yards. The 5-iron (25°) to 7-iron gap of 7° is well-gapped, which may create overlapping distance windows with similarly lofted fairway woods or hybrids. The pitching wedge at 45° provides a conventional loft window that pairs cleanly with a 50-52° gap wedge.
It's a true muscleback blade. There's no cavity in the back, no tungsten weighting, and no perimeter forgiveness. The mass sits in a solid muscle behind the face, which is why the feel is so pure and why the sweet spot is small. If you want a little more help, Sub 70 makes cavity and players-distance options in the same family that you can blend into a combo set.
The shaping and forged carbon steel feel are in the same conversation as those blades, which is the point. Where it differs is price. The 669 MB costs roughly half as much because Sub 70 sells direct and skips retail markup. You lose the brand name and resale value, but the raw performance and feel hold up against irons costing twice as much.
This is a single-digit iron, realistically for players around a 5 handicap or better who strike the ball on the center consistently. A blade will expose an inconsistent strike with lost distance and offline shots. If you're mid-handicap and just want the look, you'll likely score better with a players cavity like the Sub 70 699 or 639.
Yes. Sub 70 lets you choose shaft, flex, length, lie, and grip at order with name-brand options at no upcharge on many shafts. You won't get a hands-on fitting the way you would at a retail bay, so it helps to know your specs beforehand or use their fitting guidance. They also have a return and adjustment policy if the lie or shaft isn't right.
A blade like this pairs naturally with a stiffer, control-oriented steel shaft such as a Project X, Dynamic Gold, or KBS Tour, which suit the lower, more workable flight better players want. Sub 70 offers these and more at order. Since the head is built for precision over launch, most players match it with the same steel shaft they already play in their gamer set.
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Use as your baseline in the recommendation tool, or compare side-by-side with another set.