What does the "default shell size" option do?

When you set the "default shell size" on a tap, it changes two things about how Taplist.io works:

1. When create a new keg on this tap, we will pre-fill the form to use this size keg. (You still use a different size.)
2. When the tap is empty, and you have configured your web or TV menus to show empty taps, we'll use an illustration for this shell type.

The default setting is to use a half barrel (15.5 gallon) shell type.