Our 30cm rulers are made from lightweight plastic, and don't have the sharp edges of their steel counterparts. Used by geologists, miners, surveyors architects, these premium rulers are triangular and allows up to 6 different scales to be viewed on each ruler. The ruler has been designed with grooves along the central line to allow easy holding whether you're in the office or out in the field.
The model used by most geologists is the TRIR-04 Scale Rulers.