Model 515A is an IEPE embedded accelerometer permitting simultaneous shock and vibration measurements. 515A features an annular shear ceramic crystal which exhibits excellent output stability over time. The accelerometer incorporates an internal circuit 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 connected to the outer case of the unit. Isolated mounting washer or housing are available. Polarity inversion protection for the amplify circuit is inherent in the circuit design. The stainless-steel construction provides a lightweight hermetic housing. TO-5 three pins configuration are convenient for structure assembly and electrical connection. Compact columnar configuration is fit with most of the impact testing device. The 515B provides wide frequency response, which is ideal for dynamic vibration and shock measurement especially for lightweight structures.