fixe vacuum dimension and mesh grid in cst

hii
plz tell me how can i change the vaccum dimension it is automaticly fixed by cst for exemple cst fixed the dimension of vacuum (X:-113.75 113.75,y :-113.75 113.75 ,z -193.75 193.75) bat i want (x: -160 160, y :-150 150 ,z -192.5 192.5) with mesh gride 2.5 can any body help me
thanks in advance

You can create a box with the desired vacuum size. Then you have to unselect under mesh properties the part "Consider for bouding box" in all objects. And in the mesh properties of the vacuum box you could set the mesh grid.