Can BeSafe guarantee the usage time of the seat? (ref 15 months)

In i-size it is mandatory to transport the child rear facing till 15 months. A child safety seat has to facilitate a stature height till 83 cm. which is representative for 15 months. A child safety seat with stature height of min. 83 cm. guarantees the usage till 15 months. When a child safety seat offers only a max. stature height of 75 cm. (very normal for an infant seat), the parent has to use another rear facing child safety seat which offers a stature height till at least 83 cm.