This obstetrical wax model shows a "buttocks-first" breech presentation, in which the fetus engages the lower part of its trunk (podex) in the pelvic entrance.

The model, with detachable fetus, was commissioned by Felice Fontana, who was working on the installation of the Museo di Fisica e Storia Naturale of Florence, from the sculptor Giuseppe Ferrini and his assistant Clemente Susini.