A functional gage for use with Geo-Fact IT, consisting of a base, a spring loaded rear fence with three detent positions for special applications, a removable side fence, three removable gage pins with four Material Condition expansion sleeves, four pivoting tombstones, three coordinate system axes, and six tooling balls. Gage-It I serves to demonstrate over 25 DRF construction alternatives, a myriad of tolerancing concepts, and the Simultaneity Rule.