This beggars belief.

Adidas' new $500 ADIZERO Adios Pro Evo 1, designed for marathon runners, is billed as the company's "lightest ever innovation-packed racing shoe." Just 521 pairs of the limited-edition kicks will be made. They've gotten the weight down to just 138g (4.9 oz) using their proprietary "Lightstrike Pro" foam, and Runner's World says the forefoot rocker was "designed to trigger forward momentum and increase energy return."

On top of that, the thin, lightweight rubber outsole is smooth, with no tread; the company says it still offers the same traction as a standard running shoe and has been tested in the rain.

So here's the kicker. Making a shoe this lightweight comes with a trade-off, which is that these things wear out fast. As an Adidas product manager told RW,

"There's a card in all 521 boxes stating that the shoe is designed for 'one race – so one marathon – plus familiarization time.'"

Incredible—it's essentially single-use footwear.