Watching the NFLPA bowl and heard them mention twin brothers Brian and Brandon Dixon out of NW Missouri state. Big corners with speed. Niners need some physical big sized corners. I hope they can take a look at either one (or both) in the later rounds. I think the info on them was they were physically gifted and one of the best cover corners in the draft. 6 feet, 4.3-4.4 speed.
http://www.nwmissouri.edu/sports/boyce/2012/082812.htm