Some collections have a subscription option to receive items randomly in daily supply crates by selecting the 'collecting' option on the collection's screen.

Several collections can be completed by purchasing containers specific to that collection in the Armory using coal.

After a collection is complete, any remaining duplicates automatically convert into credits.Simply select an item you don't have instead of duplicates and exchange it exchange rates vary by collection. Duplicates can be exchanged for missing collection items.Collection items cannot be sold, so when players earn an item already in one of their collections, it is considered a 'duplicate'.

A separate album is added to a player's account for each collection after they earn the first item from a collection, but the button to see the album only becomes visible in their tab after obtaining that first item.You can usually find collection items in Containers, and each item has an equal chance to appear. Introduced in Update 0.6.5, collections are a way for players to earn unique collectibles, fill albums, and build complete collections to earn a special reward! How Collections Work

Collections world of warships wiki