File:Rambler American 1st-generation black sedan.jpg - Wikipedia, the free encyclopedia
The devices are fitted low on the body, close to the wheels. As the vehicle approaches the curb, the protruding 'feelers' act as whiskers and scrape against the curb, making a noise and alerting the driver in time to avoid damaging the wheels or hubcaps. The feelers are manufactured to be flexible and do not easily break.