A race belt is a flexible strap that has clips to secure the race numbers (bib) about your midsection.
Race belts are preferable to safety-pinned bibs because you don’t have to rip your clothing. They accommodate for speedy changes: you’re not required to doff the belt to flip the zip up or down. You’re also able to change the size. The flat shape reduces the risk of irritation on the skin. Race belts after the event still serve as useful workout tools: pockets remain accessible and numbers are visible when you do your club membership runs or major races.