The number of stages in a leg of a standing desk lift refers to the number of telescopic sections the leg of the standing desk has. Single stage legs are broken up into 2 telescopic sections, while dual stage legs are split into 3 telescopic segments. You will sometimes see single stage legs referred to as 2 stage legs and dual stage legs referred to as 3 stage legs. The telescopic sections of the leg overlap when the leg is fully retracted and separate as the leg extends. When fully extended, each segment is used to conceal the lifting mechanism inside of the leg, which protects the mechanism from debris and protects the user from the moving components of the mechanism. The telescopic segments will still overlap when fully extended to provide stability to the leg and ensure the leg is straight. When the mechanism retracts, these overlapping segments slide over each other to allow the leg to collapse.