The vibration input used is ASTM D4728 Assurance Level I. This method seeks to simulate the vibration environment of over the road trucks. This vibration profile is used because it is unusual for customers to have logged data of the actual vibrations experienced in use. A review of the available literature suggests that this is indeed a realistic input profile. Graph 1 shows this profile overlaid with data that was presented by Amgen in a paper entitled "Developing a Random Vibration Profile Standard."