While retaining a mid-cut silhouette, the Zer0.4 features a less chunky design compared to its predecessors. The Zer0.2 and Zer0.3 featured textile and synthetic overlays and a additional inner sock liner placing the Why Not lines on the heavy side of basketball shoes. However, all the extra materials which added bulk has been stripped down giving the Zer0.4 a sleeker and lighter upper. The forefoot strap which was introduced in the Zer0.3 has been replaced with what looks to be a unadjustable band. The lacing system also features bands covering the side of the foot improving lateral and medial containment.