Rapid Rules are an ingeniously simple improvement over the flat and triangle scales. It's unique shape instantly identifies the scale edge. Simply rotate the scale rod to locate the needed scale. Once located, it is retained...ready-to-use, every time you pick it up. All six scales read from left-to-right and read only one scale at a time.
Terrific tool for map and plan measuring.
300 mm long
Scales include: 1:2.5, 1:5, 1:10, 1:20, 1:50, 1:100