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 68847, Vinyl Tape 471, Blue, 1 in x 36 yd, 5.2 mil, 7100044654
3M 86340, Scotch Packaging Tape 3850-2-ST, 1.88 in x 54.6 yd (48 mm x 50 m) Heavy Duty Shipping Packaging Tape with Heavy Duty Dispenser, 7100282865 