The ExpressBox 3T provides an upgrade path to new Thunderbolt™ equipped Macs without sacrificing access to Pro Tools DSP power. Attach up to three Pro Tools|HDX PCIe cards to your Thunderbolt-equipped MacBook Pro. Currently only the Macbook Pro is offically supported but it may work with other Thunderbolt equipped Macs.
With ExpressBox 7 you can continue using your Mac Pro with confidence that your Pro Tools configuration is officially supported by Avid. The ExpressBox 7 is a 4U rack-mount chassis that connects to the Mac Pro through a PCIe card and 3m PCIe cable. The EB7 has been supported by Avid for previous generation of Pro Tools hardware so if you already have one and you want an HDX system that won’t fit into a Mac Pro then this will work for you. Note though, that currently Avid only support up to 3 HDX cards with the Expressbox 7 but if you need to run an HDX 3 and a Black Magic video card then this is the solution for you.
For more details on the exact Macbook Pro computers and the detailed specific requirements go to Avid’s Compatibility pages.