Only the KT 4004 referenced card is compatible with the Mac Pro. Mine is 2008 and the card is recognized without any driver. Having no USB devices 3, I can not judge its speed in this standard; by cons, which leads me to say that it is excellent, it is in use USB 2, it is significantly faster than USB 2 ports of the Mac Pro.
I recommend the seller who was very responsive to a request for information.