Nike Free is a minimalistic running shoe that Nike introduced for the first time in 2005. The goal was to offer runners a pair of shoes that will make them feel as running barefoot. The brand made various versions of the Nike Free, the 3.0 and 5.0 being the most popular, with the RN being one of the latest. The numbering system indicates the thickness of the midsole, 0 being barefoot and 10 a normal midsole. Traditionally, the upper is made of lightweight, breathable mesh or Flyknit material with Flywire cables. The sole is very flexible, in various patterns such as hexagonal or Tri-Star. As with most running shoes you can find the Nike Free older versions on sale, usually towards the end of the year.