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 45179, Roloc Disc Pad TR, Medium 4 in 1/4-20 Internal, 7000045281
Insize 2197, LARGE RANGE DIGITAL RADIUS GAGE, R1(4-590"/100-1500mm), R2(4-590"/100-1500mm), 697409778087
3M 45100, Roloc Disc Pad TR, Hard 1-1/2 in 1/4-20 Internal, 7000045286
Norton 66261014792 - 2" Medium Grade Aluminum Oxide Bear-Tex Speed-Lok High Strength Maroon TR Non-Woven Abrasive Disc 160 Each 