Reader, Portable Xd Reader/writer Auto-connects to USB port. Operating system software automatically recognizes the device. No batteries or AC adapter required. Compatible with both Mac and PC (Windows users will need to download driver software from software download page. Maximum read speed of 3.5 MB/sec and write speed of 0.5 MB/sec. Small size: measures 2.5" x .75" x .38" and weighs only 14 grams.