CRED
You can earn CRED by completing gigs, taking part in events and increasing your Rep level. Spend CRED to purchase HDDs (Haul Disk Drops) at the Broker.
HDD
Each HDD will contain a weapon skin and/or visual upgrade (kill counter). You'll be able to see a preview of the potential rewards from a HDD when you select it. The items will have different rarity levels: Rare, Epic and Legendary.
There are no duplicates until you have opened up all items from an HDD. Once you have unlocked all items from a HDD, any future HDD openings will award CRED instead of a cosmetic item.
Legendary weapon skins opened from an HDD will also come serialized so the first player in the world to open one will get #1, the next gets #2 and so on. To see the specific HDD drop odds and rarity guarantees select Details when you are viewing a HDD.