Is ONE Length Right For You?

Cobra’s ONE Length irons are getting plenty of attention right now. Along with Callaway’s Epic Driver, single length was the talk of the PGA Show, and the thing is, it’s more than just talk. Cobra’s VP of R&D, Tom Olsavsky, recently told me that ONE Length is exceeding Cobra’s projection by 3x.

For Cobra, ONE is moving the needle, bigly.

Some of you have told us that you’re considering single length irons. We know you’re curious. Could Cobra’s ONE length irons be right for you?

Let me refer you to the pie chart performance theory.

This theory was shared with me by a friend who works in club R&D, and while it’s incredibly simple to understand, there’s a ton of wisdom contained within. It goes a little something like this:

For any individual golfer, a new golf club will either performer better, perform worse, or perform the same as what’s already in the bag. Those are the only options, the only three slices of the pie. Mind-blowing, right?

To help you get an idea of which section of the single length chart you might occupy, we put Cobra’s ONE Length irons to the test. We had 9 golfers (and counting) put ONE Length to the test against their current gamers.

Rather than present the group averages as we often do, we’re presenting the data as 9 individual case studies. The golfers in this test include scratch golfers to nearly 20 handicappers, 30-somethings to seniors, high-speed and low-speed players. It’s a diverse group.

Before we get to the data, let’s cover some important details.

How We Tested

Cobra ONE Test-3

  • Cobra F7 ONE and Forged ONE Irons were used for this test. Golfers hit the model and flex that most closely matched what is in their bag now.
  • Lofts were not adjusted, however, lie angles of the ONE set were adjusted to gamer equivalents.
  • 9 testers hit a series of shots with 5, 7, and 9 irons from both sets. Those 3 irons were selected because they’re what you will find in Cobra’s fitting carts.
  • Some testers hit gamers first, while others hit ONE Length first. However, the 7-iron was always used to transition between sets.
  • Outliers were removed using Median Absolute Deviation. Our detection algorithms were adjusted to reduce the number of dropped shots, providing a broader sample of data.
  • Data was recorded using a Foresight GC2 Launch Monitor with HMT.
  • All testers hit Bridgestone B330-RX Golf Balls.

About our Charts

In the charts shown below, the goal was to present a significant amount of data as simply as we possibly could. I’ll leave it to you to let me know how we did.

Be sure to take note of the loft and length differences between clubs. That info is included in the launch tables for those who might want it, but we don’t obsess over it.

In the graphical portion of the chart, the tester’s gamers are always shown in black, the ONE Length is always in white. The yellow and gray bars on the larger bar charts represent the standard error. The specifics are less important, what you need to know is that the shorter the bar, the more consistent the carry distance.

Both the shot area and face impact graphics depict a 90% confidence ellipse area. Again, the important thing to remember is that smaller is more consistent.

Finally, there are a few instances where the face impact area is blank. This happens when we lost stickers (and didn’t notice) and in other situations where we failed to capture sufficient data to draw a representative ellipse.

We’ve provided observations of what stood out to us, but as always, we encourage you to dig through the data and draw your own conclusions.

Got it? Good. Let’s get to it.

Tester 1: High Swing Speed Golfer

Tester is a single-digit handicap who plays approximately 75 rounds per year. He competes in multiple club-level tournaments each season.

Age: 34
USGA Index: 4.6
Swing Speed: High
Current Iron: Mizuno JPX-850 Forged


  • The Forged ONE 5-iron launched lower (~2.5°), while differences in 9-iron launch were insignificant.
  • Tester was appreciably longer with both the 5 and 9 irons from his set. 7 iron differences are negligible.
  • Carry distance was, across the board, more consistent with gamers.
  • Centerline accuracy favors ONE Length, while dispersion and face impact areas are of similar size.
  • The data suggests no clear benefit with ONE Length, and the tester doesn’t feel they’re right for him.

Tester 2: High Swing Speed Golfer

Tester is a high teen handicap golfer who plays approximately 25 rounds per year. He’s our representative for the higher swing speed, high handicap category.

Age: 34
USGA Index: 18.5
Swing Speed: High
Current Iron: TaylorMade RocketBallz
Additional Notes: 5-iron test is hybrid (gamer) vs. traditional 5-iron (ONE)



  • As we would expect from a higher-handicap golfer, carry distances are inconsistent across all clubs.
  • Significant differences in ball speeds were observed across all 3 clubs, with ONE producing faster ball speeds except when paired against the tester’s 5-hybrid.
  • Launch and spin numbers suggest marginally better performance from the F7 ONE.
  • Dispersion areas are similar, while proximity to the target line generally favors the F7 ONE.
  • As is often the difficulty with higher handicap golfers, the data is not entirely conclusive. More testing is needed.

Tester 3: Mid Swing Speed Golfer

Tester is a low single-digit handicap golfer who routinely breaks par while playing game-improvement irons. He plays 50 rounds per year and competes in several club-level tournaments each season.

Age: 48
USGA Index: 2.5
Swing Speed: Moderate
Current Iron: TaylorMade RocketBladez
Additional Notes: Tester 3 is what we would classify as a low-spin golfer



  • This is a textbook case of what most would expect to see with ONE Length irons; the 5-iron is appreciably shorter, while the 9-iron is appreciably longer.
  • ONE consistency is better with the 5 and 7 irons, however, this tester produced significantly more consistent carry with his 9-iron.
  • Downrange dispersion favors ONE Length, however, any face impact area differences are marginal (note: tester is an excellent ballstriker).
  • 5-iron launch and spin numbers are a concern. While this would likely be mitigated to a degree by switching to Forged ONE, the 5-iron distance gap would likely widen as a result.
  • While 5-iron performance is of particular concern, there is a case to be made for ONE Length. However, the tester is comfortable with variable length and tells us single length would be a “tough sell.”

Tester 4: Low Swing Speed Golfer

Tester is a retired senior golfer whose handicap fluctuates between high single and low double-digits. He plays 100 rounds per year and plays in multiple club-level tournaments annually.

Age: 63
USGA Index: 10.7
Swing Speed: Low
Current IronPING G20



  • The 3° difference in 5-iron loft is apparently mitigated by a .5″ difference in shaft length, resulting in a negligible difference in average carry yards.
  • Appreciably lower launch was demonstrated by the F7 ONE for two of three irons tested. This, along with lower spin across the board from F7 ONE, is a concern.
  • For this tester, consistency was generally better with his current irons.
  • Downrange dispersion favors the current irons, while face impact is marginally more consistent with F7 ONE.
  • The data suggests ONE Length may not be a good fit in this case.

Tester 5: High Swing Speed Golfer

Tester is a higher swing speed scratch golfer. He plays 55 rounds per year and competes in club-level team events, but seldom competes in individual tournaments.

Age: 39
USGA Index: +.4
Swing Speed: High
Current Iron: Nike VR Forged Pro Combo



  • With the exception of the 9-iron, where Forged ONE launched 2° higher, launch and spin differences between sets were negligible.
  • As was often the case throughout this test, the ONE 5-iron was 4 yards shorter than the variable length equivalent.
  • An anomaly perhaps, the Forged ONE 7-iron produced significantly more ball speed and was significantly more consistent than the tester’s current 7-iron.
  • The Forged ONE 9-iron was more consistent while producing an additional 4 yards of carry. This is due primarily to a nearly 3.5 MPH increase in ball speed.
  • The face impact data collected suggests that Forged ONE produced more consistent strikes.
  • While far from absolute, the data suggests this tester might benefit from ONE Length irons, however, as with our previous low handicap golfer, he’s hesitant to put them into play.

Tester 6: Mid Swing Speed Golfer

Tester is a high single-digit golfer who we’d classify as an average ball striker. He plays 40 rounds per year and competes in several club-level tournaments annually.

Age: 39
USGA Index: 8.6
Swing Speed: Moderate
Current IronMizuno JPX-850



  • Tester is one of two testers where our data suggests a decisive advantage for ONE Length Irons.
  • F7 One was longer and more consistent at all 3 iron lengths.
  • Although the 5 iron produced 3.6 yards more carry, the lower launch (1.5°) may be cause for concern.
  • The F7 ONE 9-iron was 3.5 yards longer than the variable length equivalent while producing lower launch, more spin and a higher apex.
  • While downrange dispersion differences aren’t notably significant, they do suggest F7 ONE was more consistent for this tester.
  • Face impact dispersion also favors F7 ONE.

Tester 7: Slow Swing Speed Golfer

Tester 7 is a mid double-digit handicap, senior golfer. He’s the elder statesman in our group and has the lowest swing speed among participants in this test. He plays nearly 100 rounds per year and competes in several club-level tournaments.

Age: 65
USGA Index: 17.5
Swing Speed: Moderate
Current IronPING G30


  • Note the razor thin gaps between Tester’s 5 and 7 irons (gamers) and 7 and 9 irons (F7 ONE). This is unfortunately far too common among low speed, senior golfers.
  • Despite a nearly 5 MPH deficit in average head speed, the F7 ONE produced more ball speed, presumably due to more consistently centered contact.
  • Consistency (standard error bars) generally favor ONE Length, however, as suggested above, gaps are inconsistent with both sets.
  • Downrange dispersion and face impact charts suggest only a modest advantage for F7 ONE.
  • While this tester may benefit from ONE Length, the greatest improvement would likely be found through wider and more consistent gapping throughout the set.

Tester 8: Mid Swing Speed Golfer

Tester 8 rides the line between a single and double digit handicap while rapidly approaching senior status. He’s a competent ball striker who maintains a nearly moderate swing speed while playing 40 rounds per year and competing in several club-level tournaments.

Age: 63
USGA Index: 10.5
Swing Speed: Moderate
Current Iron: Titleist AP2


  • Despite the different lengths and head weights, for this tester head speeds and ball speeds are nearly identical between sets.
  • 5 and 7 iron launch conditions suggest the tester might benefit from the Forged ONE.
  • Consistency favors the Forged ONE in the 5 and 9 iron lengths, while carry distances were more consistent with the AP2 7 iron.
  • The 5-iron is particularly noteworthy as the shorter length club was significantly more consistent while producing greater carry.
  • The Forged ONE 9 iron produced lower launch, less spin, and a shallower descent angle, which makes holding greens more difficult.
  • While overall ONE performed well overall for this tester, the less consistent 7-iron and the less favorable 9-iron launch conditions are concerns.

Tester 9: High Swing Speed Golfer

Tester 9 is me, and it’s been a while since I served as a club tester. While my swing speed is above average, my ball striking most certainly isn’t. Much to my wife’s consternation, I play 50 rounds a year and compete (or at least try to compete) in several club-level tournaments each season.

Age: 44
USGA Index: 12
Swing Speed: High
Current IronPXG 0311



  • What stands out in my case is the consistency in club speed, ball speed, and ultimately the carry distance produced by the two difference sets.
  • In each scenario, there was there no more than 1.5 yards difference between my gamers and the Forged ONE.
  • Consistency (standard error) was appreciably better with the Forged ONE across all 3 irons tested.
  • Launch angle, spin rates, and apex were also higher across the board with the Forged ONE.
  • Shot dispersion and face impact areas were consistently smaller with the Forged ONE.
  • While shots hit with the Forged ONE were on average left of the target line, I suspect this is related to lie angle, shaft deflection, or some combination thereof. Adjustment is required, but because the results are consistent throughout the set, I’m not overly concerned.
  • Not surprising given my average-at-best ball striking, the data suggests I may be an ideal candidate for single length irons.

Cobra ONE Test-2

Is ONE Length Right for You?

While our data suggests few absolutes there are three generalizations we feel comfortable making.

  • Middle Handicap Golfers (call it 8-14) with moderate to high swing speed who sometimes struggle with consistent ballstriking appear to the be sweet spot for single length irons. These are golfers generally looking for more consistency across all facets of their games, and by eliminating what can be a troublesome variable, single length irons can provide just that. It’s why I’ll be starting the 2017 season with a set in my bag.
  • Slower Swing Speed Golfers and Seniors in particular, may struggle with Cobra’s implementation of single length. In the long irons the head speed lost can be difficult to overcome, and distance gains in the shorter irons may be a bit too much on a comparative basis. Substituting hybrids for long irons is at least part of a potential solution, but that brings you one club further removed from the single length philosophy.
  • Single Digit to Scratch Golfers may benefit from ONE Length. The data suggests that already excellent ballstrikers can see their consistency improve; however, these are the golfers who, among our testing pool anyway, showed the most resistance to the single length concept. We believe it can help these types of golfers, but it requires an open mind.

As with anything else in your bag, your mileage may vary and your best results are likely only achievable with the help of a proper fitting. I can’t recommend enough that you visit your local Cobra fitter and take the time to find out how the performance from the 5, 7, and 9-irons in your set compares to ONE Length.

For more information on Cobra ONE Length irons, visit For those interested in learning more about how ONE Length wedges compare to traditional models, we’ll be conducting some additional research this spring.


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