Slot Height

The two sticks were installed in either outer slot, leaving both inner slots empty for upgrades So, whatever ASUS is calling those two outer DIMM slots

In ASUS 「Memory Slots - 8」

asus prime a320mk m2 slot In ASUS 「Slot Height - 」 - Motherboards Components , you could Slot Height 2-slot

asus slot SafeSlot Core+ SafeSlot Core+ is the ASUS-exclusive PCIe slot fortified with a one-piece stainless-steel brace that shields the slot to protect it from damage