What is the thickness of NCR forms and books?

The thickness of a 2 part NCR book is 0.5" per 50 sets. The thickness of a 3 part NCR book is 0.75" per 50 sets. 

For 25 sets of a 2 part form, the thickness is 0.25", and for 25 sets of a 3 part form it is 0.375".