The Desco 19291 Digital Surface Resistance Meter is an instrument designed to measure resistance point-to-point (Rtt) or surface to ground (Rtg). Test functions include resistance measurement accuracy of ±10% (±20% accuracy for 1 x 10¹² ohms and greater), resistance range of <1 x 10³ ohms to >1 x 10¹² ohms, under load voltages of 10 and 100 volts ±5%, and electrification period of approximately 15 seconds. The 19291 also measures ambient temperature and relative humidity. Up to 100 measurements may be stored and recalled from the meter's internal memory. This includes the resistance value, temperature, relative humidity and test voltage at the time of the measurement.