Weavebird is a centre closed dobby shedding mechanism. There are no jacks, no lams, no tie ups, no limitations on shaft combinations and no limitations of pattern repeats.

Two treadles, hinged from the back of the loom,
operate the shedding mechanism. Weavebird controls both the rising and sinking shed so the tension on the warp threads is always uniformly even. Because part of the warp threads rise while the balance sink, the yarn stretch is minimized.The loom has 2 treadles.
The right treadle opens the shed and the left treadle closes it. Due to Leclerc's unique Shaft counter-weight design, physical stress to operate it is minimized.

The treadling effort to operate those Loom is similar to operating a 4 shaft counterbalance loom.