Each list has a special number to go with it and that number represents the cost of such one-time list, how many leads are on this list and how many total copies of the list are made available. An example will illustrate best how to read this special number. If a list is for sale for $16. The number "16" will means three things, the cost of the list is $16, the total number of leads on this list is 16, and lastly, there are only 16 copies are made available for purchase. Simple right? Let's take another example. If a list is on sale for $19. Then you will know right away that there are 19 leads available on this list and only 19 copies are available for purchase. Putting it in another way, the cost and number of copies of an Extra list depends on the total number of leads included on the list.