Noise and vibration isolators are used to prevent the downward transmission of vibration from a machine to a structure, the upward transfer from the structure to a sensitive machine or to isolate a complete building from ground vibration. Ground vibration may be generated by above ground or under ground passenger or freight trains, or heavy motorized vehicles, such as trucks or military equipment. The source may be industrial hammers, power plants or industrial machines, close enough to cause a problem.