Nonsense. It strengthens the oblique abdominals, but more so because it makes you feel like you're playing an instrument or a game, rather than actually doing the work itself. And without it, you could still twist your waist left and right for exercise.

I have been using it for 2 months in the gym for strengthening oblique abdominals. Good to use, sturdy construction. It can easily withstand a weight of 80 kilograms without showing signs of movement difficulty. If it was 10 centimeters larger in diameter, it would be a very good exercise machine. Unfortunately, after 1 year of use and with a maximum weight of 30-50 kilograms (used only for children), the mechanism broke.