If you have an artificial Christmas tree you really need a storage bag with wheels to keep it until next year.
Carrying a full box is quite heavy, especially if you need to keep it in the basement or attic for the year. Those stairs are killers. By using a rolling unit you can more easily move from one room or floor to another.
I picked these five because most of them come in a couple of sizes and colors and they all look quite sturdy, yet easy to move.