Lot Size - Any idea?

Does anyone have an idea about exactly what ‘Lot Size’ does (sorry if it is blindingly obvious!). It’s in my advanced inspector just below variations.

It’s not in the manual at all and can’t seem to find any reference to it. See pics - one from the GS manual. one from my version of GS

GS Manual



a lot" is a group of similar or identical items that are sold together to one buyer (a case of batteries, three dresses, a CD collection, etc.).

(source: http://pages.ebay.com/help/sell/contextual/lots.html)

eBay describes it better on a help page here:

Regards, Kristian