plastic EXTENDED MEMORY STORAGE Built-in 4 MB standard memory and 128 MB SD card (included).Update music files via micro SD card or data cable (must insert Micro SD card at the same time). Configure high-quality sound ----- built-in 8 1 watt speaker, two volumes, small and exquisite, play MP3 audio, with excellent sound quality. Two Power Methods --- Powered by three AAA batteries (not included) or USB.(both cannot be used at the same time) SENSE RANGE This sound player can detect motion up to 13 feet (4 meters), day or night.Human body induction angle up to 120 degrees. UNLIMITED APPLICATIONS - Great for seniors or needing reminders, point of sale advertising, exhibits, exhibits, door cards/welcome, writing instructions for someone while you're away, or blocking embarrassing bathroom noises.