To indicate the proper package type for your shipment you must use one of the following (in this format) in the field marked "package_type":

card
letter
envelope
thick_envelope
parcel
flat_rate_envelope
flat_rate_legal_envelope
flat_rate_padded_envelope
flat_rate_gift_card_envelope
flat_rate_window_envelope
flat_rate_cardboard_envelope
small_flat_rate_envelope
small_flat_rate_box
medium_flat_rate_box_1
medium_flat_rate_box_2
large_flat_rate_box
large_flat_rate_board_game_box
regional_rate_box_a_1
regional_rate_box_a_2
regional_rate_box_b_1
regional_rate_box_b_2

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