3M 65489, Pro Grade Precision Ultra Durable Universal Hole Sanding Disc DUH5120TRI-10I, 5 inch UH, 120, 7100202873, 10 per pack 
Insize 3287-4, GROOVE MICROMETER, 3-4″, 6928640327582
$701.92
Graduation .001″.
Measure width of grooves inside bores.
Non-rotating spindle.
Two graduations for inside and outside measurement.
Related products
Measuring/ Inspection Instruments
Insize 6140, DEPTH BASE ATTACHMENT, suitable for calipers with beam width (w) .630″, 6928640303579
$24.84