Baxton Studio Zinnia Metal Bed- 2 Sizes

Does this bed require a box spring? Or does it have a platform with slats in lieu of a box spring, so that you need only the mattress? If not required, can it support a box spring plus mattress (in case you already have one anyway)?

Per the buyer:
Box spring is not required. Slats are included. You could use a box spring but the mattress may sit very high in the frame since the bed was not designed to be used with one.