It is a Rifle shaft or Rifle Project X, a very very popular shaft, 5.0 plays very close to regular flex.
I assume you are talking about Project X golf shafts. A Project X shaft with a 6.5 flex is the equivilent of a stiff shaft.
Callaway make this shaft flex, it is designed in between a regular flex and stiff flex shaft.
It is one of the best shafts on the market, it is definitely the right shaft for anyone who is serious about improving their golf as it brings the flight of the ball right down with such a penetrating flight. It is up to you, some prefer different shafts but the project x is hard to beat.
Reviews of golf clubs such as the Callaway X-18 iron can be found from many sources on the internet. Such sources include Golf Review and Epinions. Reviews can also be found directly on Callaway's website.
In my opinion the best driver is the callaway diablo octane and the best irons are the callaway RAZR X irons.
The Callaway X-18 is an iron set of golf sticks. one can buy a Callaway X-18 in eBay, Amazon, GolfLink, etc. It can be used by amateur and professional players.
Some advantages of the Callaway X Hybrid Golf Clubs are they are customizable, the RAZR technology helps shift the center of gravity, increases distance and forgiveness.
his name is mark callaway so it is callaway his name is mark callaway so it is callaway
True Temper sells a uniflex steel shaft. This flex is soft, like a regular shaft but is supposed to be as stable as a stiff shaft and helps to increase the trajectory of the ball. Callaway and Nike have options for purchasing clubs with True Temper Uniflex Shafts.
Callaway
If you want a high quality shaft, you should look along the lines of UST, Grafalloy, Aldila or Mitsubishi. I cannot tell you which one you should get because I do not know your game/age/ability etc. The best thing to do is to go get custom fit and try out a few different shafts. Nearly all shafts have different kick points and produce different launch angles. The problem with Callaway clubs though is that shafts go through the head to the bottom of the club, some golf shops may actually shy away from fitting new shafts to these.