HELIMETRIC gages offer simplicity in obtaining accurate measurement results with high repeatability. Users do not require extensive training, as with tri-mikes, Pi Tape brand and ball gages. HELIMETRIC gages unique self-aligning feature makes operator error during measuring a problem of the past. HELIMETRIC gages leave product surfaces unchanged. Expanding ball and cylindrical plug gages can distort or damage the dimensions of the measured product. HELIMETRIC gage measurements are based on 3-dimensional geometry. The result is more accurate than measurements based on 2-dimensional circumferential or 1-dimensional diametrical geometry. HELIMETRIC gages produce highly accurate diameter readings with only one scale in either English or metric units. Mathematical operator errors introduced by the use of a Vernier scale are completely avoided.