Sabrent Premium 4-Port Aluminum USB 3.0 Hub for iMac Slim Unibody No more banding yourself to strange angle just for plugging a USB device onto your iMac Brings four more USB ports to the front side Easy to set up. Plug & Play, Hot-Swappable Exclusively designed for the iMac Slim Aluminum Unibody model released November 2012 or later. (21 inch / 27 inch / 5K)