What are the differences between HDM-AX and HD-AX height gauges [Measurement Tools] [Hight Gauge] December 06, 2023 06:34 Updated There are two main differences between the HD-AX series and the HD-AX series. ● HD-AX supports long-type scribers ● HDM-AX supports long-type scribers and can also be used with a two-point touch probe (code № 192-007). Related to Measurement Tools Hight Gauge