Rochelle Salts, which is also known as sodium potassium tartrate tetrahydrate, is identified as a crystalline solid that has a very large piezoelectric effect. This means that it has an electric charge induced on its own surfaces by mechanical deformation, whether caused by pressure, bending, or twisting. This makes the compound very useful when it is applied to various sensitive acoustical and vibration based devices. Like most other piezoelectric materials, Rochelle salt crystals will become strained when they are subjected to electric fields. They will decompose at relatively high temperatures, up to 55 Celsius and 131 Faherenheit. Because of their sensitive nature, they also require protection against moisture. The degree of piezoelectric deformation is often directly proportional to the applied electric field. It reverses as the polarity of the field is reversed. All of these properties make the compound useful in electromechanical transducers, including different types of ultrasonic generators and microphones.