Operated by a pneumatic actuator powered by a 3 bar compressed air supply - either from a compressor or a workshop air-line.
The measurement data is collected by a capacitive probe fitted just behind, and in constant contact with the measuring head.
This direct contact ensures high-quality transducer-type accuracy, even at great depths.
Measurements are taken by pressing a footswitch connected to the airline and the data is then passed automatically via cable back down the bore to the digital readout at the operator end.