Periodic Replacement 
This component manages periodic replacement. During a periodic replacement, devices due for certification are removed and replaced with equivalent devices.
You manage the devices to be replaced using the periodic replacement list, where you can also enter further devices, such as devices from an internal lot. You can choose devices from the list that must be replaced at a certain time and then create a work order or notification for those devices.
This component is optional. You require it if
you wish to certify devices individually
a lot does not pass inspection and the devices must be certified individually
You need the Certification (IS-U-US-CT) component in order to certify a device that has been replaced.