Without looking at this in depth, I would assume they are standard (but faster) PCI card slots. They are there in case you need them - if you don't so much the better as there will be less to interfere with the air flow and to create extra heat.
Surface Pro 5 News - release date, UK price, features, specs
Animator Emanuele Kabu’s psychedelic video is a stunning tribute to Lisbon city
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