Our son (7 years old, plenty of 130 cm tall) has so desired a stool. So far so good. We (the parents) have fluctuated between 20 and Sitness Sitness kid 20. In the descriptions can be found as differences on the one hand the possible seat heights and on the other hand the different max. Load capacities.
We opted for the variant "Kid", in the acceptance of the stool would be operated even by a child.
Can adjust the height of a normal-built 7-year-old boy but definitely not! - At least not down.
We can from our side only recommend the adult version to buy, because there the appearance is even better (eg profiled tires), as the Sitness kid. Priced it makes no difference. Condition: The seat height must fit.
I, the father - about 80kg (or perhaps a little more Fitzelchen) could easily put me on the stool, without which would have yielded unusually strong. The gas spring is therefore for 30-40kg bodyweight too "tight" so that you manage not to move the stool down there!
The supposedly child-friendly stool, it is only half full. - That's why 2 star deduction.
Otherwise: quality and delivery time, actually, as always, beyond any doubt!