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 9450, Disc Pad Holder 917, 7 in x 5/16 in x 3/8 in 5/8-11 Internal, 7000028549
Insize 6302, MICROMETER STAND, 6928640392467 