Brown & Sharpe 599-226-200 Micrometer Ball Attachment, Inch

Converts any micrometer with standard spindle and anvil diameters listed below to an accurate tool for measuring tubing wall thickness as well as other curved surfaces. Hardened and lapped chrome steel ball in neoprene retainer fits on either anvil or spindle of the micrometer. To measure, simply subtract the ball diameter from the micrometer reading to compensate for the size of the ball.