You can find it by looking at the link to the product purchase: http://[B]ITEM#[/B].VENDOR.pay.clickbank.net For example, for the product Teds Woodworking Plans it would be on the following link: http://[B]x[/B].tedsplans.pay.clickbank.net Where x is the item # for the main product. You can also find it on the Purchase Form (Cart) in the URL it should say somewhere ITEM=xx where xx is the item #. Is this what you are asking about?
Some vendors may have multiple products with same vendor/affiliate account. If "vendorname" is the vendor's username In that case it would be denoted by 1,2,3... etc. Like:- http://1.vendorname.pay.clickbank.net http://2.vendorname.pay.clickbank.net http://3.vendorname.pay.clickbank.net etc... 1 will most probably be the vendor's main product (if i am not mistaken)