Package Contents: BYEASY UC-109 USB 3.0 Hub Four Ports, User Manual, 30-Day Money Back Guarantee. Great Compatibility Laptop: Compatible with Windows 10/8/8.1/7 / Vista / XP and Mac OS X, Linux, and Chrome OS. ( The USB 3.0 Hub Reverse Compatible USB 2.0 and USB 1.1.). High-Speed Data Hub: Supports Transfer Speeds up to 5Gbps (USB 3.0), 480Mbps (USB 2.0), and 12Mbps (USB 1.1). Note: This hub support output max current up to 900mA.So some HDDs that need a current of more than 900mA need an external power adapter. Ultra Slim & Advanced chipset: Advanced chipset with good thermal design, will not heat even if used for a long time. USB Hub: Instantly Add Four USB 3.0 Ports to iMac, Macbook, Mac Pro / mini, Surface Pro, XPS, Notebook PC, Mobile HDD, and More.Note: This hub is not for charging devices because it supports an output max current of only 900mA.Charging very slowly.