There are many different forms of magnesium, with significant differences in their utilisation. It is not enough to know the name of a form that is well utilised, because it does not tell us two important things. The other is whether it is "fully reacted". If not, then a significant part of the magnesium is not in the form indicated in the ingredients, but remains in an inorganic form.
In our product, the magnesium is exclusively bound to the amino acid glycine, i.e. it is a "fully reacted" organic form. Our experience is that even those with sensitive stomachs do not experience loose stools or other problems with this form.