Usually child seats and infant carriers with an integrated harness or the compatible base are equipped with ISOFIX (group 0+/I). The ISOFIX connection allows for the safe, rearward facing installation of the seat using the ISOFIX brackets of the car. ("What is ISOFIX")
If only the seat is fixed in the car and the child has to be secured with the car's three-point-belt, RECARO uses the term SEATFIX. These seats are also equipped with the ISOFIX technology and connected to the metal brackets in the car. However, in this case it is more of a comfort feature that stabilises the seat if you are driving without your child in it. In fact, the SEATFIX latch arms are constructed in a way that they would even break out in the event of a crash so the generated forces can be dissipated better. If the seat would stay rigidly in its place (like with ISOFIX) the full load of energy would be forced onto the child's body. ISOFIX seats have the integrated harness and a relatively bigger, specially designed shell that absorb the energy.
Car has approval for ISOFIX but not for Seatfix?
We document all vehicle-specific approvals for ISOFIX and Seatfix. In some cases it is possible that the bigger child seats with SEATFIX are not approved despite having ISOFIX connectors. The reasons can be the inconvenient fitting of the seat, a limited belt length or that the buckle is covered by the child seat and a safe fixation with the three-point belt cannot be guaranteed. This usually involves small cars with limited space.
In a nutshell:
ISOFIX ensures the safe and easy installation of child seats of groups 0+ and I, securing the child with the car's seat belt is not necessary. SEATFIX stabilizes child seats of groups II + III but the child must be secured with the three-point belt. In any case, please get all the information about your preferred child seat prior to purchase; on our product pages, in stores and at your vehicle manufacturer.