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 95675 1/4" Male Plug with 1/4" NPT Male Thread
Insize 4809, U.S. STAND SHEET METAL GAGE, 0-36(.3125~.0070"), 6928640330162
3M 45179, Roloc Disc Pad TR, Medium 4 in 1/4-20 Internal, 7000045281
3M 26141, PPS Series 2.0 Adapter, Type S44, 3/8 Female, 19 Thread BSP, 7100158892 