The transfer time depends on the mobile device (operating system, manufacturer, version) and the size of the sound file. While most transfers should take less than 10 minutes, transferring a large file on an older device may take up to an hour. Bose recommends initiating the transfer early to ensure that it’s complete by bedtime.Sleepbuds II store sound files directly on each of the Sleepbuds. Because of the small form factor of Sleepbuds II, the amount of storage is limited. Sleepbuds II will reach a point when memory is full, and you will need to delete one or more sound files before adding a new one. The requirement to delete a sound is based on the combined size of all of the sounds on Sleepbuds II, not on the number of sounds. The size of each sound file varies. The Bose Sleep app will tell you when you need to delete a sound or sounds before transferring a new one from the Sound Library.