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 21543, Scotch-Brite Roloc Clean and Strip XT Pro Extra Cut Disc, TR, 2 in x NH, A XCS, 7100179815, 60/box
3M 45017, Diamond Grade DG3 Reflective Digital Sheeting 4091UDS,Yellow, 30 in x 50 yd, 1 Roll/Case, 7100282697
3M 50010, VentureClad Insulation Jacketing Tape 1577CW-WME, White, 99 mm x 13.7 m, 7010379907
3M 82238, Scotch-Weld Epoxy Adhesive 420, Off-White, Part B, 5 Gallon Drum(Pail), 7100001145
3M 02876, Scotch Flatback Masking Tape 250 Tan, 1 in x 60 yd, 6.0 mil, 36 Roll/Case, 7000001488
3M 76632, Roloc Disc 777F, 50 YF-weight, TR, 3 in, Die R300V, 7000045628
3M 07054, General Purpose Sanding Sponge CP-041-ESF, Single Angle, 2-7/8 in x 4-7/8 in x 1 in, Medium, 7100101551 