That's right -- the biggest iPad of 'em all has a USB 3.0-compatible Lightning port, Apple has confirmed to Ars Technica. iFixit found a controller for the new USB standard when it took the supersized tablet apart, and that came as a surprise because Cupertino didn't exactly advertise the feature. The compatibility means the iPad Pro is capable of transferring files at speeds that reach 5Gbps, whereas a USB 2.0 connection can only reach a max speed of 480Mbps. Apple had a good reason for not making a big deal out of it, though: you'll need to get an extra USB 3.0 adapter to be able to take advantage of the capability, since the tablet only ships with a cable that can handle USB 2.0 speeds. Problem is, that adapter doesn't exist yet, so you'll have to deal with slower file transfers for a while longer.

http://www.engadget.com/2015/11/13/ipad-pro-usb-3/