Foam pads supplied with the CM4 IoT Router Carrier Board Mini with Metal Cooling Case

Greetings,

The IoT Router Carrier Board Mini with Metal Cooling Case (SKU: DFR0767-1) comes with two foam cushions. One smaller one that fits nicely the CPU on de CM4 module and conducts heat to the heatsink of the Metal Cooling Case. And a larger, thicker one that i cannot place. 

What is the purpose of this foam larger pad? Where should i place that one?
 

Thanks in advance :)