Harrington played for London in the OHL. He's considered a shutdown defensemen (meaning, not much offense) but is a bit small for the role, without the reach you usually see from a shutdown guy (he's 6'0"). He logged some big minutes on the #1 pairing (with Jared Tinordi). He just turned 18 in March, so he'll have another year or two in Juniors before going to the AHL.
Another pick that will hopefully develop down the road and provide some possibilities when the contracts of Letang and Orpik run out a few years down the road.