he Tetra allows for the use of a six-point-harness from birth through to a large 4 year old. The Tetra offers exceptional features, and the highest level of safety, at an affordable price. As an A4 rear facing restraint, this child restraint allows for Extended Rearward Facing through to a large 30 month old, and then Forward Facing through to a large 4 year old. The Tetra is nice and compact at 44cm across the widest point. As a result of its compact size, this child restraint is perfect for 3 across installations and small cars.