Vivobarefoot's Primus Knit and Magna Trail shoe uppers use Merino wool yarn produced with a high twist by Sudwolle. A Stoll flatbed knitting machine develops the upper's shape and three-dimensional stitch effects, placing wool along the inside for contact with the foot.

Knitted Channels Bring Ventilation to Wool Shoe Uppers

Knitted channel structures act as vents along the sock-like upper. This construction joins material placement and airflow within the same textile, showing how a footwear upper can be engineered through stitch design as well as through its external silhouette.