The condition and alignment of gear measuring instruments can greatly influence the measurement of product gears. This information sheet provides qualification procedures for double flank testers that are used for the evaluation of radial composite deviations of gears. It discusses guidelines for alignment of double flank tester elements such as centers, ways, probe systems, etc. It also covers the application of artifacts to determine instrument accuracy. This information sheet is a supplement to standard ANSI/AGMA 2116-A05.