Package add-ons give you the ability to add extra items at the point of sale. They can be used to add member merchandise, member contributions or another package ie Add a digital package. Options let you set sizes or product options. Just use one per line.
ie M
L
XL

Where to find it
Admin area/Content/Widgets

Things to note
Include limits in square brackets = e.g.: Small Polo [100] will allow 100 purchases only.