Model 321A is a general purpose bi-axial IEPE accelerometer permitting low frequency vibration measurements. 321A features an annular shear ceramic crystal which exhibits excellent output stability over time. The accelerometer incorporates an internal circuit with in a two-wire IEPE system which transmits its low impedance voltage output through the same cable that supplies the constant current power. Signal ground is internal shielded and isolated from the outer case of the unit. Polarity inversion protection for the amplify circuit is inherent in the circuit design. The welded stainless-steel construction provides a hermetic housing. The standard M12 glass insulated connector provides long-term stability over the operating temperature range. In addition to adhesive mounting, 321A has Ø5.2 through holes for M5 screws mounting on the test object. The 321A provides low frequency response and shock resistance, which is ideal for high structure vibration monitoring under incidental shock environment. Model 321T is available for temperature measurement. Senther’s model 18T-L is a M12 connector mating cable for the sensor.