 The explanandum of a grounding-mechanical explanation is the obtaining of a grounded fact, and just as we can causally explain a phenomenon by providing a model of the inner workings of the mechanism that produces it (see Machamer et al. 2000), we can metaphysically explain why a grounded fact obtains by providing a model of how grounding facts and facts they ground are connected. We explain why a grounded fact obtains by revealing the metaphysical determination relations—examples, provided by Trogdon, include set formation, the determinate-determinable relation, functional realization, constitution and mereological realization—that hold between the constituents of the relevant facts. In other words: we explain why a fact obtains via accounting for how it is (mechanistically) grounded.