Mackie CR-Buds Series Owner's Manual page 9

 NOTE ON STATIC ELECTRICITY 
Static electricity accumulated in the body may cause mild tingling in your ears.
To minimize the effect, wear clothes made from natural materials.
Correct disposal of this product: This symbol indicates that this product
should not be disposed of with your household waste, according to the
WEEE directive (2012/19/EU) and your national law. This product should be
handed over to an authorized collection site for recycling waste electrical
and electronic equipment (EEE). Improper handling of this type of waste
could have a possible negative impact on the environment and human health
due to potentially hazardous substances that are generally associated
with EEE. At the same time, your cooperation in the correct disposal of
this product will contribute to the effective usage of natural resources.
For more information about where you can drop off your waste equipment
for recycling, please contact your local city office, waste authority, or your
household waste disposal service.