How do i get the hovering armor in mass effect 2?

in mass effect 2 how do i get the armor that hovers over your armor? is this an upgrade or class specific upgrade? its yellow i think and you see some mercs with itHow do i get the hovering armor in mass effect 2?
You have to be a sentinel: http://www.youtube.com/watch?v=IQlVjVDfR鈥?/a>How do i get the hovering armor in mass effect 2?
I'm assuming it is just different coloured shields or kinetic barriers