A PCI wireless adapter card connects to a desktop computer's PCI bus. Because the PCI bus is contained inside the computer, the unit must be opened and the wireless network adapter installed inside.
An example of a PCI wireless adapter card, the Linksys WMP54G (compare prices) is shown above. This unit is more than 8 inches (200 mm) long in order to accommodate the standard connection strip required to electrically join to the bus. The unit attaches and fits snugly inside the PCI, although the wireless adapter card antenna protrudes out the back of the computer.