Cool-er e-Reader. Diagonal: 152.4 mm (6 "), Technology: E-Ink Vizplex, Gray scale levels: 8 levels of grey. Document formats supported: pdf, rtf, epub, Audio formats supported: MP3, Image formats supported: JPG. Internal storage capacity: 0.125, 1 GB, Compatible memory cards: SD, Maximum memory card size: 4 GB. Interface type: USB 2.0. Operating system installed: Linux