There are certain warnings that the
Ear Subs have marked on them. One in particular is not to use the
Ear Subs with a device with "Bass Boost" turned on. The reason for this is not explained, but could very likely include causing damage to the
Ear Subs, one's ears or both. Also, as a precaution, you should never turn the
Ear Subs or the audio device you're using them with on or off with the
Ear Subs in your ears. Doing so can cause an audible electronic pop that can be painful if the volume is turned up sufficiently.
If you take these precautions, however, the Ear Subs can provide a very nice audio experience. I would highly recommend them to people who are old enough to take such precautions and use electronics mindfully.