What's the use of the little black box? I will adopt it.

When steam gives a gift, there is something called the gift balance. The gift balance is equal to the money you spent on buying things on steam (excluding other people's friends giving you gifts and activating games with key). Black box is equivalent to using your steam balance to buy gifts for others. This process will actually consume not only your steam balance, but also your gift balance, except that steam will not be marked. When your gift balance is not enough, even if your steam is enough, you can't give a gift, so the small black box will mark the balance of steam, which is actually your gift balance. You can withdraw steam balance through this function.