The difference is in the way the detector/stylus is moved during a measurement cycle.
The standard drive type is used by more than 80% of our customers.
The drive unit is simply placed on the surface for measurement and the start button pressed.
The retractable type lifts the stylus up from the measurement surface at each end of the measurement cycle. This keeps the stylus clear of the workpiece before and after measurement.
This type is favoured for incorporation into an automatic inspection device or a jig.
The horizontal drive type is used when it is not possible to place the drive unit into small measurement area such as a crankshaft journal which can only be measured in the horizontal direction.