The Air Jordan 21 (XX1 or XXI) PE - Black / Metallic Silver - Varsity Red - Anthracite were released on November 4, 2006, and retailed for $150. The first theing you notice about these PE’s is that unlike the other colorways, they feature a zipper which zips up to cover the lacing system. This particular colorway features a black and silver suede upper, with red inner lining, as well as the taxi design on the outsole. The look very similar to the Air Jordan 18 (XVIII). They still feature all the same technical specifiactions as the typical colorways, including a double-overlasted phylon midsole supporting four I.P.S.(Independent Podular Suspension) pods on the outsole. 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. It is not recommended that you play basketball in these, as they do not provide enough support around the ankle, and can cause severe ankle sprains.