Adhesive back rulers come ready to mount on tools and equipment. Inner edge dials have a 11/32 diameter reference hole.Graphics are black on a white background with 1 degree resolutions and come with 5 mil thick Mylar topcoat for chemical and abrasion resistance.Four Basic Styles are available:0-360 degrees clockwise,0-360 degrees counter clockwise,0-180-0 degrees dual-direction and 0-90- degrees dual direction. All are available in sizes that rangr from 3 in.-8 in. .Unlike linear rules which can be easily measured, degrees dials require special consideration. Qualifying them by degrees is dubious since the larger the diameter the larger the distance is between adjacent graduations.Additionally,the accurac at which the center point is located generating the raduis is important,but usually negligible if the chord distance is considered.To measure graduated dials we use an X-Y cross- hair matrix whose point-to-point tolerance is +/-.000 is established by rule #8594-1,and are certified by a Master Vernier Caliper certified to Federal Spec GGG-C-111C including the "NIST"Test #731-24146. All dials can be certified for an additional cost, Each dial can be indentified by a unique certification number and registered in Master Log you will recieve a letter stating the "as measured accuracy" with Certification.