it has fashionable appearance and convenient to use, this make it to be one of our most popular item. Model No. ES01 ----Imported polarized lenses ----Built-in 128MB, 256MB, 512MB and 1GB capacity memory ----Support MP3, WMA, ASF and VBR winrar format files ----Support USB2.0 full speed transfer ----Built-in rechargeable Lithium battery ----Support 6 hours continuous playing ----Filter out all UVA, UVB, UVC, and harmful blue light contours ----Rechargeable time: 3 hours