What does 6.0 mean on a Project X shaft?

A 6.0 on most current Project X shaft models -- including HZRDUS, Denali, EvenFlow, Catalyst, and IO -- corresponds to Stiff flex. On some legacy models like the PXv Tour and Project X Black, a 6.0 is Stiff Plus. Always check the model-specific chart rather than assuming a universal mapping.

What flex is a Project X 5.5?

On most current Project X wood shafts like HZRDUS Smoke RDX, Denali, VRTX, and EvenFlow Riptide, a 5.5 is Regular Plus. On the Cypher 2.0, a 5.5 is Regular. On legacy models like PXv Tour and Project X Black, a 5.5 is Stiff. The meaning varies by shaft model.

How do I choose the right Project X flex code for my swing speed?

For driver swing speed under 75 mph, use code 4.0 to 4.5 (Senior). For 75 to 85 mph, use 5.0 (Regular). For 85 to 95 mph, use 5.5 (Regular Plus). For 95 to 105 mph, use 6.0 (Stiff). For 105 to 115 mph, use 6.5 (Extra Stiff). For 115 mph and above, use 7.0 or TX. A launch monitor fitting is the best way to confirm.

Are Project X shafts stiffer than other brands?

Yes, Project X shafts generally play slightly firmer than their stated flex compared to brands like KBS or Nippon. A Project X 6.0 labeled as Stiff may feel closer to a Stiff Plus in another brand. If you are between flex codes, the softer option is usually the better choice.

What is the difference between Project X HZRDUS, Denali, and EvenFlow?

HZRDUS shafts come in multiple profiles for different launch and spin characteristics -- Black for low launch and low spin, Blue for mid launch and spin, and Red for high launch. Denali shafts are available in lighter weights starting at 50 grams for moderate swing speeds. EvenFlow Riptide offers mid-launch profiles with counterbalanced options for added stability.

Golf Tips

Complete Guide to Project X Flex Codes

Golf Club Brokers · February 2, 2018

If you've ever picked up a Project X shaft and wondered what the 5.0, 6.0, or 6.5 printed on it actually means, you're not alone. Project X uses a numeric flex code system instead of the standard "Regular / Stiff / X-Stiff" labels most golfers are familiar with. The tricky part? The flex that corresponds with each number often changes depending on the shaft model. A 6.0 in one shaft might be Stiff, while a 6.0 in another could be Stiff Plus.

Even the True Temper website doesn't offer a single compiled guide, and only some individual product pages reveal which numbers go with which flex. That's why Golf Club Brokers created this reference covering every current and legacy Project X shaft. We update it as new models are released.

How the Flex Code System Works

Project X uses a decimal numbering system that generally follows this pattern:

Code	General Flex	Notes
4.0	Senior / Ladies	Only available on select models
4.5	Senior Plus	Legacy models only
5.0	Regular	Some wood models shift this to Regular Plus
5.5	Regular Plus	Some wood models shift this to Stiff
6.0	Stiff	Most common flex across all models
6.5	Extra Stiff (X)	Some models label this Stiff Plus instead
7.0	Extra Stiff Plus (X+)	Legacy models only
TX	Tour Extra Stiff	Newer HZRDUS and Denali models

Important: This is only a general guide. The tables below show the exact flex designation for each specific shaft model, because the mappings do shift. Always refer to the model-specific table rather than the general chart above.

Which Flex Code Should You Use?

Your swing speed is the biggest factor in choosing the right flex. Here's a general guideline for driver swing speed:

Driver Swing Speed	Suggested Flex	Typical Code
Under 75 mph	Senior (A)	4.0–4.5
75–85 mph	Regular (R)	5.0
85–95 mph	Regular Plus (R+)	5.5
95–105 mph	Stiff (S)	6.0
105–115 mph	Extra Stiff (X)	6.5
115+ mph	Tour Extra Stiff (TX)	7.0 or TX

These are guidelines, not rules. A launch monitor fitting is the best way to confirm which flex optimizes your ball speed, spin rate, and launch angle.

Current Wood & Hybrid Shafts

HZRDUS Smoke RDX (Woods)

Available in Black (low launch/spin), Blue (mid launch/spin), Green (low-mid launch/spin), and Red (high launch/spin). 60g, 70g, and 80g weight classes.

Code	Flex
5.5	Regular Plus
6.0	Stiff
6.5	Extra Stiff
TX	Tour Extra Stiff

Note: 80g weight only available in 6.0 and 6.5 flexes.

HZRDUS Smoke RDX (Hybrids)

Available in Black model. 80g.

Code	Flex
5.5	Regular Plus
6.0	Stiff
6.5	Extra Stiff

HZRDUS Gen 4 Black (Woods)

60g, 70g, and 80g weight classes. Low launch, low spin profile.

Code	Flex
5.5	Regular Plus
6.0	Stiff
6.5	Extra Stiff
TX	Tour Extra Stiff

Denali (Woods)

Available in Black (low launch/spin), Blue (mid launch/spin), and Red (high launch/spin, counterbalanced). 50g, 60g, and 70g weight classes.

Code	Flex	Available Weights
5.0	Regular	50g
5.5	Regular Plus	50g, 60g
6.0	Stiff	50g, 60g, 70g
6.5	Extra Stiff	60g, 70g

VRTX (Woods)

Available in Blue (mid-low launch, firmer profile) and Red (high launch, softer profile).

Code	Flex	Blue Weights	Red Weights
4.0	Ladies	–	40g
5.0	Regular	–	40g, 50g
5.5	Regular Plus	50g, 60g, 70g	50g, 60g
6.0	Stiff	50g, 60g, 70g	60g
6.5	Extra Stiff	60g, 70g	–

EvenFlow Riptide (Woods)

Also available in Riptide CB (counterbalanced) and Riptide LX/MX variants. 50g, 60g, and 70g.

Code	Flex	Available Weights
5.5	Regular Plus	50g
6.0	Stiff	50g, 60g, 70g
6.5	Extra Stiff	60g, 70g
TX	Tour Extra Stiff	60g, 70g

Current Iron Shafts

Project X IO (Steel)

Mid launch, mid spin. 0.355" taper tip. Weight increases with flex for optimized trajectory per flex.

Code	Flex	Weight
5.5	Regular Plus	105g
6.0	Stiff	110g
6.5	Extra Stiff	115g

Catalyst (Graphite Irons)

High stability graphite iron shaft with reinforced tip section. 0.370" parallel tip.

Code	Flex	Weight Class
4.0	Senior	40
5.0	Regular	50
5.5	Regular Plus	60
6.0	Stiff	60, 80
6.5	Extra Stiff	80, 100

Cypher 2.0 (Graphite Irons & Woods)

Ultralight graphite shaft for maximum swing speed. 0.370" parallel tip (irons) and 0.335" tip (woods).

Code	Flex	Weight Class
4.0	Ladies	40
5.0	Senior / A-Flex	50
5.5	Regular	50
6.0	Stiff	60

Legacy Wood & Hybrid Shafts

HZRDUS (Original Woods & Hybrids)

Woods available in Black, Yellow, and Red. Hybrids available in Black.

Code	Flex
5.5	Regular Plus
6.0	Stiff
6.5	Extra Stiff

HZRDUS T1100 (Woods)

Code	Flex
5.5	Regular Plus
6.0	Stiff
6.5	Extra Stiff

EvenFlow (Original Woods & Hybrids)

Available in Black and Blue.

Code	Flex
5.5	Regular Plus
6.0	Stiff
6.5	Extra Stiff

PXv Tour Graphite (Woods)

Code	Flex
5.5	Stiff
6.0	Stiff Plus
6.5	Extra Stiff
7.0	Extra Stiff Plus

Project X Black (Woods & Hybrids)

Code	Flex
5.5	Stiff
6.0	Stiff Plus
6.5	Extra Stiff
7.0	Extra Stiff Plus

Original Project X (Woods & Hybrids)

Code	Flex
5.0	Regular Plus
5.5	Stiff
6.0	Stiff Plus
6.5	Extra Stiff
7.0	Extra Stiff Plus

Legacy Iron Shafts

Original Project X Rifle (Tapered Iron Shafts)

Code	Flex
5.0	Regular
5.5	Regular Plus
6.0	Stiff
6.5	Extra Stiff
7.0	Extra Stiff Plus

Original Project X Rifle (Parallel Iron Shafts)

Code	Flex
5.5	Regular Plus
6.0	Stiff
6.5	Extra Stiff

Rifle Irons (Parallel)

Code	Flex
4.0	Senior
5.0	Regular
6.0	Stiff
7.0	Extra Stiff

Rifle Irons (Tapered)

Code	Flex
4.5	Senior Plus
5.5	Regular Plus
6.5	Extra Stiff

Project X 95 Flighted Irons

Code	Flex
5.0	Regular
5.5	Regular Plus
6.0	Stiff
6.5	Extra Stiff
7.0	Extra Stiff Plus

PXi Irons

Code	Flex
5.0	Regular
5.5	Regular Plus
6.0	Stiff Plus
6.5	Extra Stiff

PX LZ Steel Irons

Code	Flex
5.0	Regular
5.5	Regular Plus
6.0	Stiff
6.5	Stiff Plus

PX LZ Tour Graphite Irons

Code	Flex
5.0	Regular
6.0	Stiff

A Note on Flex Comparisons

It's important to understand that a "stiff" flex from Project X won't necessarily feel the same as a "stiff" from another manufacturer. Project X shafts are often considered to play slightly firmer than their stated flex compared to brands like KBS or Nippon. A Project X 6.0 (Stiff) might feel closer to a stiff-plus in another brand's lineup.

The best way to confirm the right flex for your game is on a launch monitor. If you're between flex codes, go with the softer option—most golfers are better served by a shaft they can fully load rather than one that's too stiff for their swing speed.

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