An external plug-and-play solution to add up to four RS-232 serial devices to a USB-enabled computer. Use for cellphones, PDAs, digital cameras, modems, or ISDN terminal adapters through your USB ports. Many newer computers, particularly laptop computers and handheld devices, no longer include the legacy serial ports, and desktop computers have reduced the number of serial ports supported. Users with serial devices may find themselves unable to communicate with installed equipment.