They're suit slots, right now it's, you have one primary suit slot, and two secondary, the only one mentioned right now is robot legs give you faster running --- Waiting for: MH3, Metroid: Other M, SMG2, and TCON 2!!! Hebrews 11:1
Think Battlefield: Bad Company 2. You had Assault, Engineer, Medic, and Recon Class. Each has 3 'special' slots (or perks) and one for weapon customization (this is class specific). Theres special perks specific for each class, and some specials that can be used in the other classes. For example, Spec 1 could be Carbofiber armor for more life, this can be ussd for all classes. Or you can get a spotting scope to point out enemy players easier. The Spotting Scope is however, Recon specific.
Using BBC2 as an example like this makes it easier to think of what HVS is up to. --- Sparkster returns after 15 years in..... "Rocket Knight" The Conduit= 5113-1194-6759 Name= Shader