I found out through a television report on the high security of Reboardersitze. The difference from the forward-facing seats is, inter alia, that the child's spine in an accident with her back in the seat "down" and therefore less damaged. For other seats, the child is pressed with its entire body weight away from the seat in the straps. I am convinced that this is the better sitting position for baby and toddler. We had a rear-end collision, in which another car is ascended at about 40km / h on our car. The pressure on the car was immense and our trunk was heavily damaged. Our child was sitting in the Cybex Sirona Reboarder and has looked at us as if nothing had happened, as we were pushed as driver and passenger seats in neatly from our belts. My child was sitting still firmly in the seat and the seat itself is not slipped out of Isofixverankerung or has shifted elsewhere. The seat is in fact very large and heavy, but he is just too strong and has a good impact protection and it can be rotated, which is very convenient for getting in and out and buckling up the child. In addition, you can use the seat long, so that the financially acceptable. My son is from his birth until now (almost 3 years) in the seat. However, it does not depend on age but on the height, how long the Cybex Sirona can be used. My child is currently about 91 cm tall and has the maximum use of size (marked on the seat) is not reached. The Cybex Sirona can then be used forward facing seat when the child for the reverse function has become too large. Here then a stomach protection (catching body) is attached, I think this is much safer than belts. Whether the seat can be used up to 4 years, I doubt however. I had the seat take something apart and clean because my child has happened a little mishap. I want to not do every day, but have to say that I was able to clean the seat and respect very good. I can only recommend the seat. I want to add in the wake of something like the size of the seat: With us the child seat was perfect both in a Hyundai Getz and in a Seat Toledo without that there were problems with the front seat. However, that should really be tested beforehand. If the passenger needs a lot of leg space and must make his seat far back, it is in fact closely related to the child seat. You have to just try it.