He mailed the letter along with the 11 pounds of caps. He doesn’t detail if he wants the special edition of the game, which comes with the wrist mounted cell phone holster reminiscent of the “pip-boy” used in the game. However reddit has worked out that the exchange rate of caps for dollars is somewhere between 40 and 50 cents per cap, so he is mailing them approximately $800 in fictional currency in addition to the cost of mailing an 11lb box to Maryland.