Q. Do the magnets hurt my phone or credit card? No.Most electronics of similar devices such as cell phones, iPods, flash drives, etc. do not contain magnetic storage media that may be affected by magnets. We tested all types of credit cards and hotel keys for 2 years, and there was no examples of degausting credit cards, hotel keys. However, electronic tape media may be affected. It is best not to store floppy drives, video tapes, cassette tape, etc. Q. Does it affect the GPS of your phone? Mobile phone GPS is activated by satellite signals, not the force of geomagnetism, so it will not affect GPS accuracy. Q. Can I use headphones? Yes! Q. Is it waterproof? Made of water resistant material but not waterproof.