The 7000 series uses piezoresistive sensor elements which operate well at low frequencies, from 0Hz to a few hundred Hz depending upon the chosen operating range. Their low frequency response allows them to be used to measure the very slow vibrations in massive structures like buildings and bridges. Their ability to measure at 0Hz means they can also be used to study straight line acceleration in automotive or similar applications. Three electronic control and outputs are offered: bipolar amplified (with internal strain gauge amplifier), bipolar unamplified (requires external strain gauge amplifier) and three-wire 4-20mA.