Eibach Anti Roll Kit (7717.320) 08-08 Impreza WRX 4 & 5-door (2.5L Turbo H4 - Free Shipping

Was looking under my car, Wiping some of the stuff down and noticed the red sway bars up front and back. I found the part number on the back one and there is the link. My question is this, Having these installed is a plus from what I always thought. I really had no idea what kinda of things this car had done to it. So I am wondering if these are a good kit compared to others. It also says that they are adjustable, can someone please help me understand what this means and how would I adjust them if I wanted to.
I am looking to get my suspension nice and tight for fast corners and this was a nice bonus to see today. How long will these last, do I need to worry about getting new ones, My car has 80000kms on it. I have no idea when these were installed so I need to know how long they will last. Thanks