Stages Stage 1 Infant Support Seat Suitable from 4 months, it provides a padded foam support insert to aid your baby when learning to sit up. Stage 2 Activity Seat This stage includes a 360 degree rotating tray with loads of activities to keep baby engaged. Stage 3 Feeding Seat The Summer Infant 4-in-1 Superseat conveniently becomes a feeding seat including an easily removable BPA-free tray. Stage 4 Toddler Booster Seat This includes a removable soft foam insert for your growing child. It can be used as a booster by attaching it to an adult chair. What should I complement my 4 in 1 Superseat by Summer Infant with? You could complement this 4 in 1 Superseat with the Summer Infant laid back 3 in 1 lounger for when your baby needs tummy time.