The USB31000SPTW USB (Universal Serial Bus) 3.0 to Gigabit Ethernet Adapter lets you add a Gigabit network port to your Macbook or Ultrabook computer through a USB (Universal Serial Bus) 3.0 port, & features an integrated USB (Universal Serial Bus) 3.0 pass-through port that keeps your USB (Universal Serial Bus) port available for use with other peripherals. Each RJ45 port supports 10/100/1000 Mbps Ethernet & is fully compatible with IEEE 802.3i/u/ab standards. An ideal replacement LAN adapter or laptop accessory, this compact USB (Universal Serial Bus) 3.0 NIC leverages the 5 Gbps speed of USB (Universal Serial Bus) 3.0 to provide full gigabit bandwidth & also offers backward compatibility with USB (Universal Serial Bus) 2.0 systems (speed limited by USB (Universal Serial Bus) bus). The adapter supports features such as IPv 4/IPv 6 packet Checksum Offload Engine (COE) & TCP large send offload to reduce the load on your CPU. Jumbo Frames, full-duplex operation with 802.3x flow control & VLAN tagging are also supported, making this an efficient & full-featured USB (Universal Serial Bus) network adapter. Backed by a Star Tech.com 2-year warranty & free lifetime technical support. The Star Tech.com Advantage Full Gigabit bandwidth support through a USB (Universal Serial Bus) 3.0 host connection Conserve available USB (Universal Serial Bus) 3.0 ports with USB (Universal Serial Bus) pass-through Take the adapter anywhere with a portable, USB (Universal Serial Bus)-powered design