1Voice Sleep Headphones Eye Mask Memory Foam/Velvet The sound disks have an extra layering of memory foam built over them so they cannot be felt, even when you are sleeping on your side The 1 Voice Sleep Headphone Eye Mask is compatible with any phone/MP3 player and does not need a battery It is machine washable so all you need to do is remove the velvet cover and throw it into the wash The eye mask is fastened by an adjustable Velcro clasp so one size fits all.