The X Boards introduce a whole other dimension to the mix. These boards articulate from side to side and also from front to back, making a much more wobbly surface that will engage a lot of the muscles and tendons from your feet all the way up to your ears. In addition to the four point range of these boards, they also swivel, meaning they can rotate like a merry go round. This is super fun and also uses a lot of the core muscles in your sides and tummy. To take all these features up a notch, the X Board Pro is only for the most balanced and advanced users. This board is steep and aggressive, and it will wake up muscles you didn't know you had. Please try another board first unless you are an advanced user.