The handholds of plastic avoid that the device is touched by hands whereby hand heat would falsify the measuring results.
In practice you proceed with FLAT-check over the sector that you want to check and observe the deviations on the display. Depending on the requirements, a resolution of 0.1 or 1 micron is recommended for this measurement.
Fast assessing of local flatness deviation
TypeDimensions (L×W×H)WeightMiddle distance of the supportsSlide positionsMounting diameter for probe