The Cisco PIX 515E "Failover" (PIX 515E-FO) model is designed for use in conjunction with a PIX 515E-UR, providing a cost-effective, high-availability solution. It operates in hot-standby mode acting as a complete redundant system that maintains current session state information. With the same hardware configuration as the Cisco PIX 515E-UR, it delivers the ultimate in high availability for a fraction of the price.