According to the ECE R44 / 04 Standard, buckle is a quick-release device which enables the child to be held by the restraint or the restraint by the structure of the car and can be quickly opened. The buckle may incorporate the adjusting device. In other words, buckle is a device where harness system connects and locks.
According to this standard, a buckle must:
✔ Be operational by a single button or similar device.
✔ Locks when all pieces are in it.
✔ Smallest width not narrower than the width of the harness.
✔ Has a red coloured ejection button and no other part of the buckle can be in this colour for easy identification in case of an emergency.
✔ A single operation to release the child.
✔ Strength tested to withstand 4000 N for Group 0 & 0+.
✔ Strength tested to withstand 10,000 N for Group 1.
✔ Shall be capable of withstanding a minimum 5,000 open-close cycles.
UNECE bucles requires you to match the two latch plates prior to buckling it in. The two latch plates are not interchangeable.
As for FMVSS buckles, you can buckle each separate latch plate into the buckle without any problem and even swap the left latch plate to the right and vice versa.
The harnessing system consisting of the buckle and the harness are two most important parts you will need to regularly check for its condition to ensure its safety. Sometimes, there are crumbs that can fall into the crevices and this may hinder proper fastening of the buckle and may endanger your child. Thus, do periodic cleaning and maintenance to your child’s CRS.