Impact hammers are used in structural and modal analysis to determine component or system response to impacts of varying amplitude and duration. It is simply a hammer with a force transducer in its head is paired with an accelerometer on the component being tested to compare impact and response. Impact hammers are used for modal and structural behavior analysis for all types of components and systems. The most critical specifications for impact hammers are the force and pulse duration, both rated by minimums and maximums. Force is measured in pounds, kg, N and other similar units. The pulse duration, a measurement of the time the hammer is imparting a force on the object being tested, is a very short span of time, often measured in milliseconds. Another important specification is the upper limit of the frequency range. This is the highest frequency for which the response will be tested, and can be altered by using accessory tips, if available.