No MXM card in that one at all - just an empty slot.
Read my reviews of the Z370 DeskMini on the front page for an overview of the platform @dumplinknet
-https://smallformfactor.net/reviews/systems/asrocks-z370-deskmini-gtx1060-barebones-bonanza-part-1
-https://smallformfactor.net/reviews/asrocks-z370-deskmini-gtx1060-barebones-bonanza-part-2