The EMC 303.266.101A.04 2P IB 56G ENHANCED X16 SIB is a network interface card (NIC) manufactured by EMC. It is designed for use in high-performance computing environments that require fast and reliable networking capabilities.

The NIC supports two ports of InfiniBand (IB) connectivity at speeds of up to 56Gbps. This makes it well-suited for use in applications such as scientific computing, data analytics, and high-frequency trading.

The "SIB" in the name stands for "switch interface board," which means that the card is designed to be used as part of a larger switch infrastructure. The "X16" designation indicates that the card uses a PCI Express x16 interface, which provides high bandwidth and low latency connectivity to the host system.

Overall, the EMC 303.266.101A.04 2P IB 56G ENHANCED X16 SIB is a high-performance networking card that is well-suited for use in demanding computing environments that require fast and reliable network connectivity.