Yomif Kejelcha set a new world record in the 21K de Buenos Aires, wearing a shoe labeled ADIZERO ADIOS PRO EVO 3. This shoe is one of three variants approved by World Athletics.

The retail version, model KH7678, was worn by Sebastian Sawe during his historic sub-two-hour marathon in London. Two other versions, DEV and DEV1, are development shoes not available for purchase. Read more gear coverage.

Development shoes are approved for use in races but not for World Athletics Series events or the Olympics. Kejelcha's record-setting run in a development shoe is eligible for ratification. Related: Adidas Launches New Trail Shoe Inspired by Road-Racing Evo Line.

This original Runner World brief is based on reporting from Marathon Handbook. Visit the source for its complete reporting, context and any later corrections.