The Nathan AirChime K5LLA is one of the most recognisable diesel locomotive horns in North America, a five bell chime widely used on freight and passenger locomotives for decades. Railfans record it at crossings and yards, and those recordings have circulated online as standalone horn blasts for editors and soundboard users. Its distinctive chord separates it from a generic truck horn or an MLG air horn, so train fans can often identify it by ear. That recognisability keeps it popular for railway videos, simulators and meme edits where an authentic train warning is needed.