For wooden rules, the most important factor for optimum unbreakability is to use choice, well stored, highly elastic woods as the primarymaterial. For plastic rules, glass fibre-reinforced plastic provides the greatest durability. The coating on the wooden rules must be able to handle every adversity. They are protected against damp, sun and mechanical abrasion. This is the only way to ensure the scale’s good, long-term legibility.
A quality rule can be immediately recognisied by the marking on its first section. Look for four important pointers:
1. the nominal length
2. the rule’s accuracy classification which is indicated in Roman numerals
3. EU type approval certification 4. the CE and metrology marks. And last but not least, the manufacturer’s name, in other words the brand which confirms the rule’s origin and construction. The graduation scale, the most important feature, must be printed clearly and show an obvious distinction between units and tens. A double millimetre scale (on the upper and lower edge) increases the rule’s usefulness.
STABILA predominantly uses joints made from hardened spring steel, which ensure precise engagement and good spring action long-term. Catches and end cams provide strong retention, guaranteeing accuracy. Its special construction makes the joint operate smoothly over a long period. Highly durable glass fibre-reinforced polyamide joints are used on some models.