Keyspan USB 4-Port Serial Adapter allows 4 serial devices to be connected to a single USB port. It provides a simple way to add serial ports to a PC without the hassle of installing a serial card, turning off the PC, or configuring IRQs.This adapter is ideal for industrial and enterprise markets where there is a need to connect serial device to a PC for process control, data collection, or point of sale applications. It is also ideal for connecting modems, fax modems, or terminals to a server.