Heavy duty aluminum calipers. Smooth sliding aluminum measuring arms with injection molded plastic brackets. Applications for this item include log and tree measurements and we have sold them to zoos for measuring sea turtles. Black numerals and graduations Available with beams graduated in: English - Inches and 10ths on both sides Metric - Centimeters and Millimeters on both sides Combination - Inches and 10ths on one side - centimeters and millimeters on the other side. $101.25, 2/$186.00Beam Graduations: MA18 EnglishMA18 MetricMA18 Combination 24" Calipers $123.95, 2/$229.90Beam Graduations: MA24 EnglishMA24 MetricMA24 Combination 30" Calipers $139.95, 2/$259.90Beam Graduations: MA30 EnglishMA30 MetricMA30 Combination 36" Calipers MA36$149.95, 2/$279.90Beam Graduations: MA36 EnglishMA36 MetricMA36 Combination Need more information? Please feel free to contact us at 1-800-592-6940 - Ask for Extension 547 or Internet Sales.