its a box containing psro coins
u can only have a max of 30k psro coins in your inventory
if u already have 30k coins in your inventory, the new coins that u will acquire will not be added to your coins in your inventory
so trade your coins into psro box to carry more than 30k coins
example
i want to buy a +10 valk manteau and th price is 35k coins
but u can only carry 30k coins you'll have to make the other 5k coins into a box
then u can now deal..
hope i help
sorry for me english