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 65489, Pro Grade Precision Ultra Durable Universal Hole Sanding Disc DUH5120TRI-10I, 5 inch UH, 120, 7100202873, 10 per pack
Insize 0131-A120, LIGHT METER, 0.01~19.99FC, 0.1~199.9FC, 1~1999FC, 10~19990FC, 0.1~199.9Lux, 1~1999Lux, 10~19990Lux, 100~199900Lux, 6974029776557
3M 34425, General Purpose Sanding Sponge CP041-3PK, Single Angle, 2-7/8 in x 4-7/8 in x 1 in, Medium, 7100175218, 3/pack 