Counter battens - Various cross-sections

Hello.

Several carpentry companies each suggest different cross-sections in their offers, e.g.

[*]40/60
[*]30/80
[*]40/80

Does that make a difference or is it actually all the same for us?

Thank you.

80er dimensions are, in my opinion, unusual. Are you sure about that? Usually, 40/60 is used for the counter batten. Tall enough for good ventilation and wide enough for the joint of 2 load-bearing battens.