The new i-Size standard (R129), which was introduced in early 2014, has brought in additional crash testing and new technologies, which aim to ensure better safety for your child and more compatibility between car seats and vehicles. This new regulation will run in parallel with the current ECE R44/04 standard.
Car seats meeting the new i-Size standard must use ISOFIX and pass a side impact test, which isn’t required for the ECE R44/04 standard. It is also worth noting that i-Size car seats will fit into all i-Size cars and almost all cars with ISOFIX points.