The ABC’s of Golf Shaft Flex: No Longer Your Normal ARS’s

What are the different shaft flexes?

The 5 Basic Golf Club Shaft Flexes

Shaftology 101 states there are 5 basic shaft flexes (L, A, R, S and X).  For those new to golf, here is what the letters stand for in the order from the most flexible to the stiffest. The L stands for ladies flex, A for amateur or senior flex today, R is regular flex, S is stiff flex and finally X is an extra stiff flex. You could add a 6th and that is Junior or Jr for short.  The junior flex is more flexible than ladies flex due to the smaller butt diameter and especially in composite shafts due to the material.

What is a Combination Flex Shaft?

In addition to these individual flexes, there also exist golf club shafts that are either made to possess two (or more) separate flexes within a single shaft.  These are commonly called “combination flex” shaft and used to cut down on inventory.

Combination Flex Manufacture's Designinations
L and A combination flex  A&L or A/L flex
R and S combination flex   R&S or R/S flex
A and R combination flex A&R or A/R flex
S and X combination flex   S&X or S/X flex

Specialty Shaft Flexes

The flexes mentioned above have pretty much stood the test of time since shafts first received flex designations, but that is not the case anymore.  Here is a primer to get you up to speed with all the new designations you may encounter.


The LL flex is the most flexible of all adult shafts, which is one flex softer than a traditional L flex shaft.


M flex has been used by TaylorMade to designate "Mature" or what most manufacturers call senior flex.


Not to be confused with sub-flexes for True Temper’s Gold series (R200), the R2 flex designation is mostly found in high end Japanese manufacturers such as Fujikura and Graphite Design.  The R2 is the equivalent of the modern day A flex shaft.  Instead of calling it amateur or senior flex which is ability or age related, the R2 shaft flex is simply a softer shaft than a standard regular flex for those with reduced swing speeds.


The R3 nomenclature was also derived from the Japanese manufactures and would be the modern day equivalent of L or ladies flex.  The name R3 takes out the sex of the individual in the fitting equation and instead relates it the player’s swing speed much the same way that ladies grips are now referred to as undersized. The R3 flex is the gender neutral term for those with the lowest swing speeds.


The SR flex designation can be confusing because some may look at the SR as being short for senior flex. Or others may think it could be a combination R and S flex model depending how it is cut.  It is neither.  If it were a combination flex, most manufacturers would have it look like R&S or R/S.  The SR actually stands for strong regular.  Another way to put it, it is in-between a traditional R and S flex shaft as a single or discrete flex.


Unless you see characters like / or & in-between the S and X, then it is not a combination flex shaft like some of the FST steel iron shafts.  Rather the SX flex is a discrete flex that is in-between a standard S and X flex shaft.


The “T” as we will show in a couple of examples refers to Tour flex.  So the TS shaft flex designation is short for Tour Stiff.  This is a flex that is stiffer than traditional S flex but softer than X flex within the same family of shafts.  TS may be equivalent or a cross-over to the SX designation.


Ditto here, the TX flex indicates Tour extra stiff and is stiffer than a traditional X flex.


The double X– yes, there is such a category for those with very high swing speeds in which standard X is just not stiff enough.  The XX shaft flex may be equivalent or a cross-over to the TX designation.

2X, 3X

The 2X flex shaft is the same as the XX, but just another way to see it.  You might find these specialty shafts for long drive competitors.  There are also shafts designated as 3X or essentially a XXX flex which would be the stiffest shafts of all.

F1, F2, F3, F4 and F5 flex

These flex designations have been adopted by UST and Aerotech in recent years.  The “F” is short for flex and the number indicates flexibility with the lower number being more flexible.  The conversions to traditional flexes are as follows:

F1 Flex = Ladies flex, F2 Flex = Senior flex, F3 Flex = Regular flex, F4 Flex = Stiff flex and F5 Flex = Extra Stiff flex.

In the UST Recoil series, you could find a F0 Flex which was the same as the LL flex or one full flex softer than Ladies.

True Temper R200, R300 and R400, the S200, S300 and S400, and the X100, X200 and X300

As mentioned before in True Temper’s Gold series, you might see sub-flexes or where the shaft would be weight sorted by the manufacturer to tighter tolerances.  For example, True Temper would make a Dynamic Gold S flex shaft.  Due to manufacturing tolerances, some of the shafts would weigh a little less than the mean or average and others might be heavier.  The ones in the average weight range would be labeled S300, those that were lighter would be labeled S200 flex and the heavier models would be S400. Yes, years before tighter manufacturing tolerance occurred, you could find S100 and S500 flexes listed at the further end of each weight and flex spectrum too.

Weight is a minor component of steel shaft flex (within the same shaft pattern). The heavier the shaft, the thicker the walls would be and therefore the stiffer the shaft flex. For example, a S400 would be stiffer than a S300.  However, an X100 would still be stiffer than a S400 flex.

5.0, 5.5, 6.0, 6.5 and 7.0 flex

Unlike most shafts on the market that are labeled R, S or X flex, the Project X shafts are created just a little differently. Dr. Joe Braly is credited with bringing the concept of frequency matched golf clubs into being in the 1970s.  It was Braly's concept of assembling clubs on a rising incremental frequency slope that established that shafts should not only become stiffer as they became shorter, but more importantly they should also provide a uniform progression in frequency between club to club.  It was Brunswick Golf that patented this process that is still used today in the Rifle series of shafts that is now manufactured by Project X.

The number of flexes (or called frequency coefficients) originally ranged from 3.5 to 7.5 flex, but the range now has been paired down to the 5.0 to 7.0 range. In addition, the conversions to traditional flexes have been softened.  For example, a 43” driver that oscillated 255 cpm (cycles per minute) was described as an S flex or had a frequency coefficient of 5.5. Below are the modern shaft flex number conversions.

5.0 Flex = Regular, 5.5 Flex = Regular Plus, 6.0 Flex = Stiff, 6.5 Flex = Extra Stiff, and 7.0 Flex = Extra Stiff Plus

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