Add two USB 3.0 ports to your current system... up to 10x faster than USB 2.0. Backward compatible so you can connect all existing USB 2.0 devices. Both ports are bus-powered: so most external drives can be used without a power adapter. Ideal for transferring music: movies: and videos to/from external drives. Simple to install... just slide into any open PCI Express slot. Connect up to 127 devices per port by cascading multiple USB 3.0 hubs.