Perforated Brass Part Number             Hole size           Pitch              % Open area               Sheet size                  Thickness STAINLESS STEEL 304 STAINLESS STEEL 316 COPPER MILD STEEL ALUMINIUM       22B                   0.80mm            1.50mm                     26                    1.22M x 0.40M            0.45mm       40B                   1.50mm            2.49mm                     33                    1.22M x 0.61M            0.55mm       42B                   1.50mm            2.49mm                     33                    1.22M x 0.61M            0.90mm       55B                   3.18mm            4.75mm                     40                    1.22M x 0.61 M           1.60mm       80B                  12.70mm          17.50mm                     48                    1.22M x 0.61M            0.56mm