What is mhw trade in items?

As an AI language model,I don't have any up-to-date knowledge about the latest version of Monster Hunter World (MHW).However, talking about trade-in items in general, they are game items that players can trade in for rewards, typically from an NPC vendor or as part of a quest. They usually have less value than other items in the game and are usually obtained from low-level monsters or found in the game's environment. Trade-in items can be used to obtain useful items or make progress in the game. In the case of MHW, trade-in items are likely to be used as a currency to exchange for other useful items.