Free use of uniforms and socialization with classmates are possible advantages

It make each child the same no one is better or richer so there all equal

If it's a smaller child or infant, place one on the middle of the chest and on the child's back. (if it is a bigger child with enough room for two, place one on the upper right/your left of the chest, and one on the lower left/your right) the pads should never touch each other. 

They need to contract and relax