The PRH-200 is a Taylor reflex hammer with a piezo sensor attached to perform reflex measurements and record strike magnitude.
The Threshold of the impact needed to elicit a response can be determined by measuring the amplitude of the strike.

The Taylor Hammer is the most common type of reflex hammer used by doctors and nurses.

A piezo sensor is attached to the head of the hammer. When compressed or stretched, the cable generates a voltage that is somewhat proportional to the force of acceleration/deceleration;
there must be an impact to generate a response signal—just swinging the hammer in the air will not produce a response.

The PRH-200 is used as a patella reflex hammer for recording impact stimulation of the patellar tendon.