Simply because PIRT enables you to Explore, Experience and Enjoy 4 Black Sea Basin countries (Armenia, Bulgaria, Georgia and Turkey) at once.
You only need 3 steps to take:
Select one or more option from existing 10 different itineraries
Start your trip from 1 of the “PIRT countries”, learn its neighbor countries and end your trip in the 4th country to make your learning of the region complete
Enjoy learning your neighbor and learning yourself