Nike unveiled Shox technology in 2001 when they released the Nike Shox R4 running sneaker, Nike Shox BB4 basketball sneaker, and the Nike Shox XT4 cross trainer. Designed to absorb energy and return it to the wearer, all three sneakers featured hollow foam columns built into the midsole with a TPU heel counter. Since then, Nike has released many sneakers with Shox technology and they are still considered extremely comfortable sneakers today.