The ACU-ARC Adjustable Ruler excels at determining the radius of existing curves for duplicating parts or dimensioning drawings. Just slide the pointer to match the curve and then read the radius in inches under the pointer. The 12-in. ruled edge adjusts easily to draw curves of any radius from 6-3/4-in. to 200-in. (17-cm. to 500-cm. in the metric model). It can also find centerlines and center points of curves. The Acu-Arc is made in the USA of a rugged new plastic material that's both flexible and durable. The bridge-like design allows the edge to bend, yet hold a firm edge. It's a perfect example of Yankee ingenuity.
Hoyle Products, Inc., www.hoylegrips.com (800) 345-1950, Acu-Arc Adjustable ruler – inches or metric, $45.