Article of footwear

An article of footwear comprising:

• an upper having a first ground facing surface;
• a primary sole part having a first foot facing surface, and a second ground facing surface, the first foot facing surface comprising a plurality of openings, each opening of the plurality of openings defining a volume extending in a vertical direction from the first foot facing surface towards the second ground facing surface having a closed end;
• and
• a secondary sole part having a second foot facing surface and a third ground facing surface,
• wherein the secondary sole part is arranged between the upper and the primary sole part and extends into the plurality of openings in the first foot facing surface of the primary sole part,
• wherein the plurality of openings extend from a heel area of the primary sole part to a forefoot area of the primary sole part in a plurality of laterally extending rows of openings,
• wherein the primary sole part further includes:
• a first set of grooves extending along the second ground facing surface in a lateral direction of the second ground facing surface, the first set of grooves being spaced apart from each other by the plurality of laterally extending rows of the plurality of openings, and
• a second set of grooves extending along the second ground facing surface in a longitudinal direction of the second ground facing surface, such that the second set of grooves transversely intersects the first set of grooves,
• wherein respective inner surfaces of the first set of grooves define respective longitudinally facing sidewall surfaces of the plurality of openings,
• wherein respective inner surfaces of the second set of grooves define respective laterally facing sidewall surfaces of the plurality of openings, whereby the plurality of openings are enclosed on all lateral sides, and
• wherein the primary sole part defines a mould cavity of the secondary sole part, where the plurality of openings of the primary sole part define the mould cavity of the secondary sole part.