text: Due to its material properties, Terfenol-D is excellent for use in the manufacturing of low frequency, high powered underwater acoustics. Its initial application was in naval sonar systems. It sees application in magnetomechanical sensors, actuators, and acoustic and ultrasonic transducers due to its high energy density and large bandwidth capabilities, e.g. in the SoundBug device (its first commercial application by FeONIC). Its strain is also larger than that of another normally used material (PZT8), which allows Terfenol-D transducers to reach greater depths for ocean explorations than past transducers. Its low Young's modulus brings some complications due to compression at large depths, which are overcome in transducer designs that may reach 1000 ft in depth and only lose a small amount of accuracy of around 1 dB. Due to its high temperature range, Terfenol-D is also useful in deep hole acoustic transducers where the environment may reach high pressure and temperatures like oil holes. Terfenol-D may also be used for hydraulic valve drivers due to its high strain and high force properties. Similarly, magnetostrictive actuators have also been considered for use in fuel injectors for diesel engines because of the high stresses that can be produced.