When you go to add a product to a bunch of T-shirts, and you click Make Selections... A whole bunch of products come up, and they each have a drop-down with 0 to 9. What does that do?

When I just had a Basic store, that was just a check box for me to click. Doesn't seem to be much explaining what the numbers do. Can someone fill me in? Thansk!

In basic shop you are allowed only one of each. In a premium you can have more than one. The 0-9 allows you to pick more than one of the same product. You might want to do that, for example, if you want to display more than one color of a particular product.