Measure radius of external arc, arc angle of measured surface should be larger than 90?
Resolution .0005″/0.01mm
Buttons: on/off, set, inch/mm, preset (+, -)
Automatic power off, move the digital unit to turn on power
Battery CR2032, Data outputMade of stainless steel
Supplied with pin gage for zero setting

Norton 66623325035 - 2" 120 Grit Fine Grade Aluminum Oxide Vortex Rapid Prep Green TR Non-Woven Surface Preparation Disc, 50 Each
Insize 4807, ANGLE GAGE SET, 6928640319341
3M 07053, General Purpose Sanding Sponge CP-040NA, Single Angle, 2-7/8 in x 4-7/8 in x 1 in, Fine, 7100110752
Dynabrade 78317 2" Dia. x 1" W x 1/4" Shank, Fine, NWN DynaBrite Wheel, 10/pack
3M 19769, Utility Cloth Sheet 314D, 9 in x 11 in P150 J-weight, 7000000357
3M 97421, Aluminum Foil Tape 3380, Silver, 72 mm x 45 m, 3.25 mil, 7010375681 