The FST Pro 125 Stepless X-Stiff is heavier than average for steel iron shafts at 4.41 oz (125 g), while its 3° torque is on the higher side. Its mid launch / mid-low spin flight profile and very stable / low-twist character make it best suited to medium-fast or fast tempos.
Iron shaft specifications
FST · Pro 125 Stepless X-Stiff · Iron Shaft
Material: SteelFlex: X-StiffWeight class: Tour-heavy (120+ g)Flight: Mid launch / Mid-low spinTip: Taper tip
4.41 ozWeight
3°Torque
X-StiffFlex
Low-MidLaunch
Material-matched benchmarks
How this shaft compares
Numeric comparisons use steel iron shafts in this database.
Weight
Above average
4.41 oz
Weight is above average among steel iron shafts in this database.
Torque
Very high
3°
Torque is very high among steel iron shafts with published numeric torque.
Balance point
Very low
51.5%
Balance point is very low among comparable steel iron shafts.
At a glance
Shaft profile
MaterialSteel
TipTaper tip
LaunchLow-Mid
SpinMid-Low
StabilityVery stable / low-twist
Tempo fitBest suited to medium-fast or fast tempos
Overview
Model information
| Manufacturer | FST |
|---|---|
| Model | Pro 125 Stepless X-Stiff |
| Category | Iron Shaft |
| Catalog year | 2026 |
| SKU / code | FS0088 |
| MPF rating | 5C1H |
Full specifications
Technical details
Weight & flex
Weight4.41 oz (125 g)
Weight classTour-heavy (120+ g)
FlexX-Stiff
Torque3°
Bend pointhigh
Kick pointHigh
Tip stiffnessstiff
Tip flexfirm
Butt flexfirm
Balance point51.5%
Build & dimensions
MaterialSteel
Tip typeTaper tip
Tip diameter0.355 in (9 mm)
Butt diameter0.6 in (15.2 mm)
Shaft lengthVaries by club
Length range41.0-37.0 (derived discrete set) in (104.1-94 (derived discrete set) cm)
Parallel tip lengthN/A — taper-tip design
Club rangeIron set, typically 2i/3i-PW
FinishChrome / polished steel (family-based)
Flight & feel
LaunchLow-Mid
SpinMid-Low
Trajectory / spin profileMid launch / Mid-low spin
Stability profileVery stable / low-twist
Launch assistanceNeutral launch assistance
Feel profileCrisp steel feedback, very firm/stable through impact, substantial tour-weight feel
Relative weight positionAbove average for steel iron shafts
Relative torque positionVery high for steel iron shafts
Player fit
Tempo fitBest suited to medium-fast or fast tempos
Transition fitHandles aggressive transitions well
Control vs speed biasControl / consistency biased
Long-iron playabilityNeutral long-iron playability
Short-iron controlStrong short-iron and wedge control bias
Likely swing-speed fitFaster iron swings / stronger players
Target playerFaster swing speeds / stronger players seeking low launch, lower spin and maximum stability
Golfer fit summaryControl / consistency biased; best suited to medium-fast or fast tempos; mid launch / mid-low spin.