Trade Up
The Trade Up system allows exchanging 10 items of the same rarity for a single item of a higher rarity. Only weapon and utility skins can be used in the Trade Up system. All knives, gloves, agents, and emblems are excluded from the Trade Up system, meaning they cannot be used for or gained from a Trade Up.
Reward chances are based on the collections of items used for Trade Up. This means that the skin you get from the Trade Up can be from any of the collections of skins you use in the Trade Up. The chances of which collection your skin will come from are shown when selecting skins for the Trade Up.

You can filter items by rarity, collection, and type to select the items you want to use in Trade Up. Only skins with the same rarity can be used, meaning you cannot use 9 common skins and 1 uncommon skin, only 10 common skins or 10 uncommon skins for example.
The introduction of the Trade Up system means you can now own duplicates of any item, including weapon skins. Duplicates will appear separately in the Trade Up menu and will no longer be converted into Blue Tokens. This allows you to use your duplicates to get items with higher rarity.
If you have any remaining Blue Tokens or are wondering what happened to them, check out our article on Blue Tokens for more information.