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 28713 ROLOC DISC PAD TR, HARD 4 IN 5/8-11 INTERNAL, 7010298961
3M 26018, PPS Series 2.0 Adapter, Type S11, 3/8 Male, 18 Thread NPS, 7100135942
3M 26016, PPS Series 2.0 Adapter, Type S9, 16 mm Male, 1.5 mm Thread, 7100135330
3M 54763, SandBlaster Right Angle Grinder Multi-Layer Disc, 4 1/2 in 36g 9678, 7010384119 