Tiny and comfortable, Bose Sleepbuds II work with the Bose Sleep app to deliver relaxing sounds to help you fall asleep, and use Bose noise-masking technology so you stay asleep. Perfect for sleeping on planes or in loud environments - even side sleepers (like me!) can use these as they rest entirely within the ear. These don’t play music or podcasts - just content from the Bose sleep app. Wireless. Rechargeable battery: case has lithium ion battery and buds have NiMH batteries (last 10-12 hours) so they charge in the case. Requires USB-C to USB-A charging cable (not included). These were a gift to my daughter and never used.