2 panels
-- 2 panels options: 18 x 20 in 2 panels of 9 x 20 18 x 21 in 2 panels of 9 x 21 20 x 22 in 2 panels of 10 x 22 20 x 23 in 2 panels of 10 x 23

3 panels
-- 3 panels options:

4 panels
-- 4 panels options: