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 65488, Pro Grade Precision Ultra Durable Universal Hole Sanding Disc, DUH5100TRI-10I, 5 inch UH, 100, 7100202876, 10 per pack
Insize 4807, ANGLE GAGE SET, 6928640319341
3M 26138, PPS Series 2.0 Adapter, Type S42, 3/8 Female R-Angle, 19Thread BSP, 7100135930 