 The Vapor also featured an external heel counter which was very uncommon at that time as well as a "glass" filled outsole called NikeFrame, inspired by track sprint spikes and designed to spring back into shape after push-off.According to the booklets inserted into the box with each pair, the shoe showed a 3% decrease in the time to cover a 20-metre sprint compared to other boots.The Mercurial Vapor II was released in January 2004 in two colourways