Mackie MP-320 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.