Products in this family can be used to make a variety of basic electrical and electronic measurements, and are one of the most fundamental tools used in the electrical or electronic trades. Price points, feature sets, and performance levels vary significantly, though most devices are capable of measuring both AC and DC current and voltage, as well as testing for circuit continuity. Additional features often found include measurement of temperature, resistance, capacitance, and frequency. They are generally incapable of making measurements at high speeds, and as such are used primarily for measuring low-frequency phenomena or quantities that can be meaningfully represented as time averaged values, such as the amount of current flow in an AC-powered appliance.