本儀器主要用于各種圓柱形、球形、平行平面等精密零件的外形，內孔尺寸的直接測量和比較測量，亦可進行內外螺紋中徑等特殊測量，是各級計量室中必備的基本長度計量儀器之一。Itisoneofthebasiclength-measuringinstrumentsformetrologicaldepartments.Itisapplicableforbothdirectandcomparativemeasurementsofouterandinnerdimensionsofworkpiecessuchasparallelplanes,spheres,cylindersandbores.Byusingvariousaccessories,itcanbeusedforspecialmeasurements,suchaspitchesofmalethreadsandfemalethreads.