How large are you making vert screens?

For those of you that are building screens into your verts, how large are you making the insterts depending on the size of the tank and all.

[Ridge]

In my 10 gallon uprights I use a vent at the top that is 1 1/2" x 8". I am in the process of making some lexan inserts as the humidity loss is higher than I want. The inserts I will make will still have some holes drilled in them to allow for ventilation but should slow down my humidity loss.

[TopGunJags01]

I made mines 1', like the actual ventilation holes is 1' by 8'. It works perfect and my humidity is around 80 - 90.