Portable unit's maybe a handheld pulsar / receiver. Monitor or monitoring systems are used to continuously detect or measure flaws, thickness or corrosion in production line, plant or field applications. Important performance specifications to consider when searching for conductivity meters and resistivity meters, NDT include measuring range, accuracy, number of channels or probes, and operating temperature. The measuring range is the range of conductivity values that can be measured by the device. The accuracy of an analytical measurement is how close a result comes to the true value. In a conductivity meter, the accuracy is the expected minimum absolute value in conductivity units that the measured value is close to the exact value. The number of channels or probes specifies the number of channels of the unit, or the number of probes that can be connected to the device. The operating temperature refers to the full-required range of ambient operating temperature. Other features common to conductivity meters and resistivity meters, NDT include programmable or digital control unit, real-time imaging capabilities, and printer ports. A meter with programmable or digital control controlled by computer programs or by other digital methods. Real-time imaging capabilities can produce images in real time that normally can be displayed on monitors, or can be stored in storage devices. A printer port can be connected to produce hard copies of data.