Freely adjustable volume The volume can be freely adjusted according to personal needs Take care of your baby's hearing, parents are more at ease Attention: Please use the 1.5V AAA non-rechargeable batteries. DO NOT use this piano mat near the high temperature environment. Please remove the batteries from musical piano mat if it not in use for a long time. Please DO NOT use disssfferent types of batteries or mixed old and new batteries simultaneously. Music Enlightenment Music has been proven to be a great tool in building a child’s memory! And the musical mat can promote kids' music intelligence.