Keep your event items and base game items by sending them to the vault to access later.
If you have 100 green medkits the vault will accept them all but return only 50 back to you.
Event items will not have a penalty upon transfer so 100 spoopy flashlights equals 100 spoopy flashlights.
These items stored in The Vault can be sent to any survivor or killer of your choice.
The point of this is to reduce what goes to waste upon prestiging. To keep event items that we all like to collect.