Referred to as “locked trades,” a box allows you to profit from differences in the value at expiration and the price of the underlying instrument. Ignoring commission costs, you will make a profit if you can buy them for less than the value or sell them for more. Additionally, this can be an alternative to closing out positions at possibly unfavorable prices. Because there are so many legs, the cost of commissions can make it unfeasible, though.
Long Box: Long call A, short call B, long put B, short put A. Value = B – A.
Short Box: Long call B, short call A, Long put A, short put B. Value = A – B.