The Air Jordan 21 (XX1 or XXI) - White / Metallic Silver - Black were released on June 3, 2006 and retailed for $180. They feature a simple all white leather upper, and may seem bland at first glance, but the technology behind them definitely make up for whatever they lack in looks. They feature a double-overlasted phylon midsole supporting four I.P.S.(Independent Podular Suspension) pods on the outsole. They also feature a quilted lining/bootie, which provides a better fit. There is a carbon fibre shank plate in the midsole, as well as an improved I.P.S. technology with interchangeable heel Zoom air pillars or encapsulated air pillars. These encapsulated air pillars came inside the special packaging of the shoes, and many ordinary people had no clue how to use them, but for those who took the time to read the instructions and cared what they were for, they definitely used them as planned.