Help on rain lock panels

We are doing a remodel on a shopping plaza. They are changing the from look of the plaza, they are adding four new towers and increasing the hight of the walls. They offer me to do the parapet walls, currently they have 26ga Galvalume PBR panels. I gave them pricing on the new panels with the same materials but, they also want me to include pricing for rain lock panels… I have never estimate rain lock panels… I don’t want to make a mistake, please advice… Thank you