3M 03123, Pro Grade Precision Edge Detailing Dual Angle Sanding Sponge, 24302TRIP-XFDA, 2-7/8 in x 4.5 in x 1 in, X-Fine, 7100170066 
Insize 4002-B5, ANGLE GAGE BLOCK, 5′, 6928640354267
$414.18
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?).
