The N7 Suit is a reskin of the Security Suit introduced in Dead Space 2. There are two variations of the suit, one for Isaac Clarke and another for John Carver. Isaac's suit is dark grey, and features the N7 logo and red and white stripe on the right side of its chest and shoulder respectively. John Carver's suit also features the logo, but has a predominantly red color scheme.
Aside from the new color scheme, the suit is unchanged shape-wise from its original Security Suit model, with a flexible health bar that runs down the spine as opposed to the shell-like pod featured on the new suits featured in Dead Space 3.
The N7 Suit, like the Planetcracker Plasma Cutter, is a promotional item, rewarded to those who has a Mass Effect 3 save game on their PC/PS3/Xbox360 hard drive. It can be accessed as early as the first Suit Kiosk. you can just download a mass effect 3 save file for the pc and place it under \Users\(username)\Documents\BioWare\Mass Effect 3\Save just google dead space 3 mass effect save
Note that the player must also own Mass Effect 3 if this suit were to be unlocked on PS3 and Xbox360.
The N7 Suit's descriptions mentioned it as an armor worn by "Shepard" in a 21st century Earth fiction, replicas of it were distributed by Cosplay Intergalactic Inc.
Displayed on the suit's hologram projector is the same display of Isaac and Nolan Stross present in all variations of the Security Suit from Dead Space 2. This is most likely due to the fact that the N7 Suit is merely another texture swap of the Security Suit. The Dead Space 2 style health bar is still present on this suit.