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 70147, Hookit Center Water Feed Disc Hand Pad, 3 in x 7/8 in, 7000045752
Standard Abrasives 42658, A/O Flap Wheel 625105, 3 in x 1/2 in x 1/4-20 in 60, 7010369119, 10 per case
Insize 1185-300A, DIGITAL OUTSIDE POINT CALIPER, 0-12"/0-300mm, 6940561959918
3M 26110, PPS Series 2.0 Adapter, Type S24, 1/4 Female, R-Angle 18
Thread NPS, Side Cup Mount, 7100135940 