My phone call had been to determine if they were 'sealed' or could be opened, and whether they were 'graded' in any way (as only the front was advertised and we didnt know what was on the back).
They were neither sealed nor graded.
Someone later pointed out a 'slab' has to only contain one item. If something was graded then that grade is not going to apply to all the items - they will be different.