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 64465 Scotch-Brite Durable Flex Belt, 1/4 in x 24 in, A FIN, 7000121133
3M 01331, Stikit Gold Film Disc Roll, 6 in, P120 grade, 7010292680, 75 discs per roll
Insize 1120-1501WL, DIGITAL INSIDE GROOVE CALIPER, 1.38-6"/35-150mm, built-in wireless, 6928640384806
3M 26016, PPS Series 2.0 Adapter, Type S9, 16 mm Male, 1.5 mm Thread, 7100135330 