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?).

Dynabrade 98265 3/8" Female Coupler with 3/8" Male Plug Assembly
Insize 4635-111N, WHITWORTH PIPE THREAD RING GAGE(G SERIES), G 1 - 11_ NOGO, 6928640375477
3M 03140, General Purpose Sanding Sponge CP041-6P, Single Angle, 2-7/8 in x 4-7/8 in x 1 in, Medium, 7100101537, 6/pack 