The new cybex sirona m2 i size complies with the new european requirements and regulations for car seats ece r 129 this new i size regulation states that children aged 15 months and under must travel in a rear facing infant car seat which is seen as the safest mode of transport by many experts including consumer and health organisations such as which the adac and the german independent consumer testing organisation stiftung warentest when using the cybex sirona m2 i size the child can b