- Jil sander's new spring and summer Mule shoes. This hollow shoe is really beautiful. The instep uses a pleated elastic band, which adds a bit of smartness and cuteness to the minimalist style, making it a bit difficult to find. Refuse, soft and comfortable and not easy to scratch your feet! Upper: cowhide, lining: sheepskin, sole: Italian thickened genuine leather outsole, size: 35-39 (40 is custom-made and cannot be returned or exchanged),