Perfect Pi Diameter Circumference Tape Measure - Imperial and Metric Tape Measure 1/2-inch by 12ft / 3.5m - Use for Measuring Cylindrical Objects - (Pipe Tape, Tree Tape) Model DCT120 - Amazon.com
Meterex Diaflex Diameter Tape Measure with Flexible Steel Blade and Plastic Case, Dual Reading in CM and Inches with 2m Range and Blank Space Before Zero - Measure Diameter of Trees and
Diameter Tape Measures - Keson
Forestry Suppliers Metric Fabric Diameter Tape Model 283D/5M | Forestry Suppliers, Inc.