You must see this everywhere: rodbuilding blogs, mannufacturer websites… Even so I’m going to go ahead and write these few lines. I’m writing this because the naming used to describe the action of a rod is one of the worst inspired on the planet. Anglers all over the planet get these descriptions wrong, at least they understand them wrong, and can’t hold it against them.

The naming for describing the rods action, their curvature while under load, will take you wild places, and make you think about the rigidity of the blank, which can’t be furthermore away from the truth.
For e.g.: I’ve recomended Lamiglas Certified Pro rods for fishing crankbaits, and these Salmon&Steelhead blanks are described as Fast or even Ex-Fast in action. Most of the times I get the following reaction:”Well if it’ a Fast or Ex-Fast rod, isn’t it for fishing soft plastics?”… My answer always mesmerises, when it begins with e BIG NO. Fast or Ex-Fast doesn’t describe the blank’s rigidity, it simply describes the curvature of the blank under load. 
The best e.g. I have is an old fiberglass Fenwick from the 60’s I have, whose action is described as Ex-Ex-Fast. What does this mean? Is this a rod for fishing soft plastics? Is this a rigid fiberglass? NOT EVEN CLOSE! It simply describes the way the blank bends under load, which means that it flexes more in the first quarter of the blank. This is simply put a rod for fishing crankbaits and other moving baits. No way you’d use this for fishing soft plastics.
As it follows, a Fast or Ex-Fast rod doesn’t mean the rod is rigid, it simply means it flexes more towards the tip just as seen in the picture above. It transits much faster in the backbone of the rod/blank. For e.g. Japanese anglers more often prefer and utilise Regular or Regular-Fast (Moderate or Moderate-Fast) rods/blanks for fishing soft plastics, but made out of ultra high modulus carbon or graphite.  These rods/blanks have nothing to do with fishing reaction lures.
I hope what I wrote above makes sense… The conclusion is that a Fast or Ex.Fast rod/blank doesn’t mean you’ll be getting a rigid setup. And more often than you might think a Ex.Fast rod/blank has a finer tip than a Fast rod/blank.