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 27722, Cubitron II Roloc Durable Edge Disc 984F, 80+, YF-weight, TSM, Maroon, 3 in, Die RS300VM, 7000045179, 200 per case
Standard Abrasives 714179, Aluminum Oxide Handy Roll, P240 J-weight, 1-1/2 in x 50 yd, 7100050575
Insize 7232, SCRIBER, 6928640320088
3M 91004, Drywall Sanding Sponge CP-042-4PK, Single Angle, 4-7/8 in x 2-7/8 in x 1 in, Fine, 7100111452, 4/pack 