The Model 87 from Endevco Corp., San Juan Capistrano, CA, is a low-noise compact seismic accelerometer designed to measure ultra low-level seismic events and low-frequency vibration on structures and objects. The 6 oz. sensor is hermetically sealed and is available in 1 V/g or 10 V/g sensitivities. It provides near DC frequency response flat to 0.05 Hz, F.S. output voltage of 5 V, overload protection to 400 g, low-impedance output at <10 Ω, and a temperature range of –4°F to 212°F.