>What exactly do they do? I mean fully adjustable...what
>exactly do they adjust.

Teins are ride height adjustable and the shocks have 16 way adjustability for ride firmness. They are a true coilover, which means the body of the shock itself is the coilover, with a threaded perch you can raise or lower to adjust the ride heigh to almost 3" lower. Because they're designed as coilovers, they differ greatly from the the traditional coilover/strut setup which suffer ride quality issues. Even at their best (ground control, etc) they still can't match the performance, handling, and ride quality of a true coilover. I've got my car about 2.5 inches lower than stock height, and ask the guys out there, anyone lowered that much is bound to have gripes about ride quality, bottoming out, and bouncing off the bumpstops. Hop in my car, and you'll feel the difference in a heartbeat. The ride is firm, but much much smoother. Bumps aren't bone-jarring, and I'm not constantly bottoming out or hitting the bumpstops. I have a friend with an S2000 with fairly respectable drop springs, and until you ride in my car, it feels fine...but when compared, my car makes it feel like he's got cut springs.

As for the firmness of the shocks, 16 settings may be exaggerated for most people, but I'm not gonna complain. Come on, we're metric guys...isn't it better to have 1-19 instead of 5/8, 1/2, 1/4, 3/16? I'm currently on setting 11 of 16. I first started at 8, and was really impressed, but felt like a few more steps couldnt hurt. 11 is where I'm happy, and I can take offramps like an indy car

Before you spend a dime on suspension, make sure you get a ride in a car with true coilovers. You're gonna spend just about the same amount and the difference is night and day. Tein has those new basic coilovers that are height but not damper adjustable, those are only 750. If nothing else get these...you'll be much, much happier when you do.