While earlier USB specifications defined maximum length, later standards only define the cable characteristics. Provided the cable meets those characteristics (as do the supplied Avocor cables), then to ensure fault-free operation with maximum throughput, the following should not be exceeded for a direct connection:
USB 2.0 < = 5M USB 3.0/3.1 < = 3M USB C < = 1.8M Should you wish to extend the USB, you can use extenders. We would recommend always using extenders that are separately powered and fully comply with the USB specifications. When using the extenders, remember each end of the extender will act as a separate USB hub. You should always take this into consideration to ensure the maximum number of USB hubs and devices allowable in the USB specification are not exceeded (and in some cases, your computer USB chipset may allow fewer devices than the specification allows).