Designed to expand upon the built-in ports on either machine, the Surface Dock is hugely useful if you want to connect to a display (or two) with its mini DisplayPorts, get online via Ethernet, or plug in numerous USB accessories. It connects via the Surface Connector, powering the computer and drawing data from the port simultaneously. Of course, if you want HDMI or VGA connectivity, you’ll need to buy a dongle.
The Surface Dock is rather expensive for what it is, but getting one for free changes that proposition a bit. This is certainly an appealing offer if you’re teetering on the line of buying a Surface Laptop or Surface Book 2. Unfortunately, the Surface Pro isn’t included as an eligible machine.