The new cybex sirona m i size complies with the new european requirements and regulations for car seats ece r 129this new quoti size regulationquot states that children aged 15 months and under must travel in a rear facing infant car seat44 which is seen as the safest mode of transport by many experts44 including consumer and health organisations such as which44 the adac and the german independent consumer testing organisation stiftung warentestwhen using the cybex sirona m i siz