Manufactured from Crystal Clear Perspex This dimensionally stable material is particularly beneficial in the field of technical drawing. . The ruler with a millimetre division of 400 mm has a facet for precise line guide. abrasion-resistant deep embossing of the millimetre division for years of precise work. 23. labelling and labelling. Conforms to Ö standard, box contents: Aristo ruler AR1434, length 40 cm, packed in plastic protective case