Starrett 247MA Micrometer Ball Attachments, 5 mm Diameter, 6 Diameter Anvil And Spindle, Metric

Easily applied by snapping on to end of either anvil or spindle, thus permitting two attachments to be used together Balls are hardened, measure 5mm in diameter and move freely in the retainer, insuring positive contact with anvil and spindle The diameters, 5mm of each ball used must be subtracted from the micrometer reading Applied for No. 2M, No. 230M micrometers and No. 263M micrometer heads, 6mm diameter anvil and spindle