A multi-purpose functional gage set for use with Geo-Fact I, consisting of a base, a spring loaded rear fence with multiple detent positions for special applications, a removable side fence, three removable gage pins with four Material Condition expansion sleeves, five tombstones representing alternative Datum Feature Simulators for the slot in Geo-Fact I, three coordinate system axes for illustrating the outcome of Datum Reference Frame establishment processes, and six tooling balls, representing Point Datum Target Simulators. Gage-It I serves to demonstrate over 25 different Datum Reference Frame establishment processes, a wide range of residually mobile Datum Reference Frames and tolerance zones illustrating the Rule of Simultaneous Requirements, the impact of Datum Feature imperfections on the process, the differences between “aligning” and “clocking” Datum Features, and much more. A copy of the SmartGD&T Personal Trainer & Exercise Manual is highly recommended as a source for myriad exercise examples.