The Structure is Nike's support trainer, and the 26 is a full redesign. A full-length ReactX midsole sits under a midfoot system that wraps the arch and heel, slowing how fast your ankle rolls inward without the hard medial post older stability shoes used. If your form falls apart late in a long run, this is the shoe that keeps the ride honest.
It is heavy, at roughly 321 g, and it feels planted rather than lively. That is the trade you make for the support.
It is not a fast shoe, and it is not for you if you already run comfortably in a neutral trainer — you would carry the weight and get nothing back for it.