The listing, EGYPTIAN WALKING ONIONS~9 ROOTED BULBS~HEIRLOOM has ended.
Egyptian walking onions are very unusual.
They grow their babies on the top of their stalks.
Then they get heavy, fall over and root themselves on the ground, walking around your garden.
The parent bulbs in the ground will also multiply. they should be divided every few years, once established.
Once established you will have onions for life.
These are heirloom.
The first year you will not get top sets.
So don't pull your onions the first year.
The second year, you will get top sets that will fall over and root, or remove them and plant where you want them.
These should be planted as soon as the ground can be worked.
They will be packaged with out the pot but with the potting soil.
please plant immediately.
They are not particular about soil, unlike regular onions that are heavy feeders. As for their size, not sure.
Here is a link with info about walking onions:
http://www.ehow.com/how_4480804_grow-egyptian-walking-onions .html
The last pic in the photos is a stock photo of mature (parent)onions with top sets.