Anyway I finally bought it for an incredibly low price, I didn't expect that as I'd seen a U-shaped one which was quite expensive. But in the near future I'll buy that one as well, as a reward for university exams from parents :-)
It requires patience but if you don't want to have the result too soon you'll be surprised how easy it is, compared to knife.
Working with wood's just pure pleasure.
Everytime I find out something like this , I fall in love again :-)