Child restraint systems with ISOFIX fittings come equipped with a third anchor point know as a Top Tether. This anchor is a type of belt which secures the car seat to the back part of the rear seat backrest, or to the trunk of the car, depending on the model of car.
If the CRS does not have a Top Tether, then it will come with a support leg which is stretched out in order to be anchored to the car floor. With this support leg we can position many ISOFIX child car seats in a rear-facing position, which is the safest position for young children.