Our flaps are designed to extend out from the fender's edge enough to be effective, to hold their shape at speed and block the most damaging kind of tire spray. They will bend, flex, give, even scrape and drag without breakage. Flexible, but with a semi-rigid characteristic that allows them to retain their shape at speed and effectively block tire spray (we're not into flappy mud flaps). Our material is a proprietary blend of polymers that will hold up in the most extreme conditions, hot or cold.