This European Standard specifies the performance requirements and testing methods for standard letter mail trays, as specified in the classification below. The trays should be used to facilitate the exchange of international mail. The technical specification of the trays should be such that the performance requirements specified herein are met and tests specified herein successfully completed. The technical specifications of trays as such however, are beyond the scope of this standard. This standard covers a one-size universal letter mail tray suitable for carrying C4, C5 and C6 mail: Table 1 - Letters (maximum accepted sizes) Height Width C4 353 mm 250 mm C5 173 mm 250 mm C6 120 mm 250 mm The trays are suitable for containing C4 mail stacked in a horizontal plane and for stacking C5 and C6 mail vertically.