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

Insize 1120-3001WL, DIGITAL INSIDE GROOVE CALIPER, 1.97-12"/50-300mm, buit-in wireless, 6928640384844
Dynabrade 78600 3/8" Dia. x 2" W x 1/8" Center Hole, 120 Grit, 100/pack
Dynabrade 94990 1/4" Female Composite-Style Coupler with 1/4" Male Plug Assembly
3M 65086, Scotch-Brite Diamond Wheel, 6" x 1" x 1" 645DC, 7010329878
3M 24049, Wetordry Cloth Disc 281W, P1000 YF-weight, 8 in x NH, Die 800JM, 7000045052
3M 27468, EMI Copper Foil Shielding Tape 1181, 1 in x 18 yd (25,40 mm x 16,5 m), 7000132169 