Dark Matter Armor are Powered Suits created by a Certain Magical Company that utilize Darker than Black's ability -- Dark Matter -- for their creation. It is also how the group of Dark Side affiliates who utilize them are referred as.
The Dark Matter suits are pitch black with some tones of gray and are slim-fitting; to the point that it gives enough of a person's figure that you can determine someone's gender by closely observing. There are some variations in suit constructs, probably to show difference in rank.
The suits are equipped with masks of a platinum color that is twice the height of a human face. The masks do not have eye or mouth holes and shine with artificial light -- and the words "Dark Matter" are inscribed upon them. They are designed for mobility and therefore lack heavy-duty armor and can be shot through with proper weapons, as shown when Alisha and Jiao fought and killed twelve of them.
Dark Matter's strength lies in their masks, which have been forged out of the Dark Matter Darker than Black is producing while hooked up to Black Light. The masks allow attacks with multiple pairs of pure White/Black wings that spread from them, akin to Darker than Black's own seraph wings. The wings are very durable and very sharp, to the point where Rachie thought of them as "something that can cut through everything", using the wings as either shields or blades can easily make up for the suits lack of body armor or additional offensive equipment.
It is stated that the masks and the wings that spread out from them are made of the same material. The wings that the Dark Matter masks unleash are described as organic. Strangely, Darker than Black's ability is described as something that controls the inorganic.