For unsurpassed stability and quality performance, look to Simpson's rectangular style meters. The rectangular style offers a popular look with sharp, beveled edges and glass windows for easy viewing. AC units have either iron-vane or rectifier type movements. All ranges are calibrated to 60 Hz. Iron-vane type current meters have frequency ranges of 25-800 Hz (for ±1% deviation from value at 60 Hz). All rectifier types have 25 Hz to 10 KHz range. Three different standard sizes of 2-1/2", 3-1/2", and 4-1/2" are available to measure various AC current ranges including amps, milliamps, and microamps. This style meter is ideal for many other electrical functions.