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 26583, Accuspray Refill Pack for PPS Series 2.0, Green, 1.3 mm, 7100152953
Insize 6140, DEPTH BASE ATTACHMENT, suitable for calipers with beam width (w) .630", 6928640303579
3M 07053, General Purpose Sanding Sponge CP040-12-CC, Single Angle, 2-7/8 in x 4-7/8 in x 1 in, Fine, 7100101245 