I assume they have been extra to pass the CE / FCC certification. They are protecting against electromagnetic some Component of the circuit including the power stage over the motherboard and also the I/O board (most likely power also) within the CM3 adaptation board. Generally is a minor pricey: https://financefeeds.com/pretiorates-thoughts-56-buy-when-the-cannons-thunder-and-sell-when-the-angels-sing/