MEElectronics Air-Fi Metro AF71 - Manual (Page 6)

Turn down the volume prior to using the headphones; adjust the
volume to the desired level once they are connected. Do not use
headphones at high volumes for extended periods of time as doing so
will result in permanent hearing damage. It is advised you keep
volume levels moderate to low at all times for your safety, even when
loud background noise is present.
Please visit www.osha.gov for more info.
Follow all laws governing use of headsets while driving, cycling,
walking, and/or running. Do not insert both earphones while driving a
car, cycling, operating machinery, or performing other activities that
require hearing surrounding sounds.