Abstract: Disclosed is a gage for measuring the nominal diameter of an elongated tubular member having a plurality of circumferentially spaced apart radially outwardly extending flutes. The gage includes a first gage part having a generally semi-circular segment with a flute engaging surface and a similar second gauge part including a generally semi-circular flute engaging surface. The first and second gage parts are joined together, preferably by a hinge, to form a generally circular ring adapted to fit about the tubular member. Each flute engaging surface includes a plurality of stepped arcuate flute engaging portions that are spaced at radii from the center of the ring corresponding to nominal diameters to be measured.