have been tested:
+ USB serial converter
+ USB Webcam
+ USB AVR ISP
+ USB hard drive (with external Netzeil, a 2.5 hard drive is running no longer!)
+ Mouse
+ Tastertur
+ USB sound card
everything runs without problems, even times have two 5m cable plugged together -> 10m and the USB sound card connected to the PC, running everything :)
really great for the price