IDK, but I think they want you to raise the shipping space a bit more, and fill in the new shipping space with more stuff. That is, buy more. Though it's a freebie so I don't complain
BTW I'm getting
Turnigy Taipan Fiberglass V-Hull 385mm (Hull Only)
Product ID: Taipan385
Normal Price: $61.08
NOW: $0.00
Which is a huge deal, but you need a motor, ESC, impeller, battery, RX, and Tx which HK wants you to buy.
If I were to buy a motor, ESC, impeller, battery, RX, and Tx, THEN, I'd like them to throw in the hull for free.