Hardness Tester ASTM B647-84 (2000) Measuring Range 0 to 20HW Resolution +/-0.5 HW Indenter 0.79 Features Measure Hardness Soft Metal Aluminum Alloy Reading Dial Anvil 0.024 in to 0.23 in Thickness Requirement of Flat Workpiece and Wall Thickness Requirement of Tube Workpiece Includes Hardness Test Block Wrench