3 and not all of the devices I tried for music use the minimum version, the enhanced app that is offered would not run on anything less than the minimum but it did not detract from the amazing listening experience. The battery lasts forever and once it dies you can easily change them out or charge if you use rechargeable. I spent over an hour in the bathroom and in the end it only consumed 10 percent of the battery. This helped straighten out my beard hairs and make me look reasonable. I got a flashing bluish-green light and tried troubleshooting it with different cables and charging blocks but to no avail. Overall, Im pleased with them. - La detección del sueño, si tienes bajas pulsaciones, falla. Im so disgusted with Dre, that I hope I followed enough of Amazon guidelines for this review. We struggled to find first walking shoes for little one as his feets were very wide fit. They look great, clean easily and even when my feet swell a little towards the end of the day I can still slip them on without trouble.