Cisco's eight-port serial port adapter (PA-8T) delivers high-density WAN connectivity for enterprise and service provider networks. It provides up to eight full-duplex serial interfaces for the Cisco 7200 and 7500 Series routers. The eight-port adapter requires only a single slot in a Cisco 7200 Series router. For Cisco 7500 Series routers, it requires one of the two available adapter slots on a Versatile Interface Processor (VIP2). Its high density doubles the number of available ports in the same space as the four port adapter (PA-4T+). This enables up to sixteen ports per chassis slot in VIP2-based systems.