The PHR- has a digital display and allows the user to monitor the test force application electronically. The means of operation is broadly similar to that of the PHR- with the benefit that the test time application is also displayed electronically giving the user the opportunity for more reliable test cycle times and additionally the result is displayed digitally at greater resolution than the PHR-.

The PHR- is a manual analogue device applying the test force entirely under control of the user. The instrument is magnetically clamped to the component, the pre-load is applied by means of the user turning the handle on the top of the device until the gauge shows the requisite pre-load. The hardness read-out is then zeroed by the operator and the handle turned until the full test force is applied. Once the dwell time at full load has been achieved the user winds back the test force until the gauge shows the pre-load is being applied once again and the hardness value then read from the indicator.