means they will ship in-stock items every Tuesday. This helps you save some money on shipping as well as reducing the amount of packages you get as they will bulk. How it works is, for example, if you ordered a number of books and they were all in-stock on the same week, rather than getting multiple packages sent, they will bulk and send it all the following Tuesday. I would recommend this option if your items are all on stock and/or released around the same time as each other.