The USB31000SPTW USB (Universal Serial Bus) 30 to Gigabit Ethernet Adapter lets you add a Gigabit network port to your Macbook or Ultrabook computer through a USB (Universal Serial Bus) 30 port & features an integrated USB (Universal Serial Bus) 30 pass-through port that keeps your USB (Universal Serial Bus) port available for use with other peripherals Each RJ45 port supports 101001000 Mbps Ethernet & is fully compatible with IEEE 8023iuab standards An ideal replacement LAN adapter or laptop accessory this compact USB (Universal Serial Bus) 30 NIC leverages the 5 Gbps speed of USB (Universal Serial Bus) 30 to provide full gigabit bandwidth & also offers backward compatibility with USB (Universal Serial Bus) 20 systems (speed limited by USB (Universal Serial Bus) bus) The adapter supports features such as IPv 4IPv 6 packet Checksum Offload Engine (COE) & TCP large send offload to reduce the load on your CPU Jumbo Frames full-duplex operation with 8023x flow control & VLAN tagging are also supported making this an efficient & full-featured USB (Universal Serial Bus) network adapter Backed by a Star Tech 2-year warranty & free lifetime technical support Gigabit Ethernet port through a USB (Universal Serial Bus) 30 20 connection Integrated USB (Universal Serial Bus) 30 pass-through port IEEE 8023 8023u & 8023ab (10BASE-T 100BASE-TX & 1000BASE-T) compatible Crossover Detection & Auto-Correction (Auto MDIX) IEEE 8021Q VLAN Tagging support Jumbo Frame support Supports Checksum Offload (IPv 4 IPv 6 TCP UDP) & Large Send Offload Compact lightweight design for maximum portability