This is a very simple--but critical--part of the PDU selection process that can cause trouble during installation. What kind of input plug should the PDU have? What types of output receptacles should the PDU have? The problem is that connectivity types vary so widely, and many people are unable to identify even the most common plugs and receptacles. Because of the limitations, many customers will either overlook this part of the selection process entirely or will simply make an educated guess or assumption. If it is guessed wrong, the customer will then have to return the PDU because they can not connect their devices to the PDU or they can not connect the PDU to the wall outlet.