Folding Meter Sticks (plastic) This folding meter stick folds into fourths on three hinges for easy storage. Calibrated in Metric units and enable us to measure objects, its important to know how to read a ruler because you never know when you might need to measure furniture or other objects. Metric rulers only deal with centimeters and millimeters. Inches are a part of the American system, but the metric ruler uses the metric system, which is based on decimals.