Specifications Add-on SD card for expanding the storage space USB2.0 port Capacity: 128MB / 256MB / 512MB/1GB/2GB(optional) Plastic body Built in Lithium Battery Output power: 10mW + 10mW Frequency response: 20HZ20KHZ Signal/Noise: 95dB Support Windows 98/2000/XP Mac OS 10 Linux 2.4.2 Accessory: USB cable headphone user manual charger