Thinking about expanding the family in the future? The Bugaboo Donkey3 duo extension set base includes the basic hardware parts to convert your Bugaboo Donkey3 Mono into a side by side double stroller: the seat frame, sun canopy wires, and clamps, leather-look grips, carry handle, and the rain cover. The seat and bassinet fabric are not included but are available to be purchased separately. You can combine this item with the Bugaboo Donkey3 Mono and the Bugaboo Donkey3 duo fabric set to create a complete stroller for two children of different ages.