The space between the two layers of the Longs that creates a friction free environment and controls the pressure gradient difference in the lungs

The answer would be true.

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.