Being 6'5" with short legs my center of gravity is quite high. I never really get rid of that twitchy feeling in my Explorer, so I wanted an exercise to work on my balance. I ran across the Greenland balance stool online a couple weeks ago, and built one last Saturday. You sit on it with legs straight or bent like they are in a kayak. It really does feel like a tippy kayak. It's easy to use when just sitting there watching TV and quite fun as well. Only problem is whenever I want to use it the kids take over and I have to wait until they go to bed for my turn.