The AnthroFlex NA305 anthropometric diameter tape measure has a 6mm x 2m flexible steel blade with blank space before the zero. The top side measures length in millimeters, and the reverse side calculates the diameter that corresponds to the length. Ideal for diameter, circumference, small trees, pipes, pi, etc. SPECIFICATIONS: Blade width: 6mm; Blade length: 2 meters; Blade material: enameled flexible steel; Units of measurement: metric Shell material: ABS plastic