Bently Nevada evolution of our current Acceleration and Velocity sensing tools began with velocity sensors that offered a self-generating moving-coil design used by geologists to measure movement in the earth’s crust. Today we still refer to “seismic” sensors in a nod to their origin. These early sensors yielded to the introduction of rugged solid-state accelerometers, later ushering in today’s integrated accelerometers that deploy signal processing circuitry for output signals using velocity rather than acceleration. Our experience and expertise developed over decades offer a selection of first-rate casing-mounted accelerometers and velocity sensors with a variety of models for specific applications.