Accuracy: ?2″.
To inspect protractor, taper gage, index plate, index head and goniometer, can also be used to set angle.
Made of special alloy steel, hardness HRC64, high stability, wear resistance and easy combination.
Can be combined to any angle with interval 6 seconds after combination (6″, 12″, 18″, … , 360?).

3M 45024, Diamond Grade DG3 Reflective Digital Sheeting 4083UDS, Fluorescent Yellow Green, 24 in x 50 yd, 1 Roll/Case, 7100282395
Standard Abrasives 726017, A/O R8 Straight Precision Cartridge Roll, 1/2 in x 1-3/4 in x 1/4 in 180, 7100098766 