The Cisco 1-Port OC-3/STM-1 POS Port Adapter is ideal for service providers or large enterprises that need to deploy line-rate OC-3/STM-1 connectivity with choice of optics.The Cisco 1-Port OC-3/STM-1 POS Port Adapter combines superior performance and an innovative design to provide the following benefits: Line-rate performance; Automatic protection switching (APS) failover between cards; Modular, pluggable optics.