The USB31000SPTW USB 3.0 to Gigabit Ethernet Adapter lets you add a Gigabit network port to your Macbook or Ultrabook computer through a USB 3.0 port, and features an integrated USB 3.0 pass-through port that keeps your USB port available for use with other peripherals. Each RJ45 port supports 10/100/1000 Mbps Ethernet and is fully compatible with IEEE 802.3i/u/ab standards. An ideal replacement LAN adapter or laptop accessory, this compact USB 3.0 NIC leverages the 5 Gbps speed of USB 3.0 to provide full gigabit bandwidth and also offers backward compatibility with USB 2.0 systems (speed limited by USB bus). The adapter supports features such as IPv4/IPv6 packet Checksum Offload Engine (COE) and TCP large send offload to reduce the load on your CPU. Jumbo Frames, full-duplex operation with 802.3x flow control and VLAN tagging are also supported, making this an efficient and full-featured USB network adapter. Backed by a StarTech.com 2-year warranty and free lifetime technical support.