A chair for (mostly) girls only!
Your pelvis gets moved forward and you end up sitting straight and use your back muscles.
In the beginning this might hurt like hell after some minutes (I actually got sea sick) but add some minutes sitting on it per day and get used to it. The good thing is that it has this awesome 3D spring. While typing I'm actually moving left, right, back, forth and don't sit still.
If you want to check out the details about the chair, click HERE. It's definitely a good investment and if you have a cheap chair you can switch to if you back gets too tired the better.
Otherwise ask me anything if you have any questions.