23A503 up for sale is a new part that came from a closed machine shop , flat anvil to be used on  a wilson rockwell tester unit , this unit measures 1.415    long , the mount diameter that fits in the machine is 0.745 just under 3/4 ,the flat surface top is 2.482 diameter about 2 1/2 the top anvil is 0.649 thick just over  5/8 well made parts not sure exact manufacturer could be a wilson OEM part but not marked anywhere , , comes loose as shown in the photos , note the photos represent the unit you will get we got  a group of these in from a closed GM auto plant , appears to be a new part from factory surplus  , see our store we add new items weekly , thank you for viewing our store and supporting a USA based small hometown business , thank you rwk