This rule shows Standard Inches in increments of 64ths of an inch photographically printed along its top edge. It has numbers every 32nd of an inch, every 16th, every 8th and so on— for the entire length of the rule. Metric Millimeters & Centimeters, in half-mm markings, are printed along the 30 cm bottom edge. In scientific circles, mm and cm are referred to as metric measurements or SI units (from the French Systéme Internationale). To round out this classic Schaedler Rule, we have placed Printers Points & Picas down the center. These are the original points & picas still used in the printing industry — where six picas are equal to .99576 of an inch, not quite a whole inch. This entire Single A rule is coated with a blue color tinge so it will be easier to find on a cluttered work-table.