12 and 18 inch flexible center rule set.
The Chappell Universal Center Rules are made from .029” stainless steel and are flexible enough to work on round logs and uneven surfaces. The front sides have a decimal inch scale divided in the 1/4, 1/2 and 3/4 inch, with minor divisions in .05". The scales on top and bottom start from opposite zero points, allowing the rule to be worked from either side without flipping it over and reading upside down.