3M 87449 Silver Depressed Center Grinding Wheel, T27 Quick Change, 9 in x 1/4 in x 5/8-11 Center Hub Thread, 7010409732, 20 per case 
Insize 4168-8E, STEEL STANDARD BALLS, 5/16″, 6940561981469
$13.52
To measure angle and diameter of taper holes
Material: tool steel
Hardness: HRC63
Diameter accuracy:?.00012?
Roundness .00004″
Supplied with manufacturer inspection certificate.
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