IEC socket Power Distribution Units (PDUs) are used in data centres and server rooms to distribute power to multiple devices or equipment within a rack. They typically have numerous IEC sockets or outlets that allow you to connect power cords for different devices, such as servers, switches, routers, and other equipment.

Vertical and horizontal rack mount versions are two types of IEC socket PDUs that differ in their mounting orientation.

A vertical rack mount PDU is designed to be mounted vertically within a server rack, typically on the side or at the frame’s rear. Multiple IEC sockets are arranged in a vertical column to use the rack space efficiently.
On the other hand, a horizontal rack mount PDU is designed to be mounted horizontally within a server rack, typically at the front or rear of the rack. It has multiple IEC sockets arranged in a horizontal row, making plugging power cords from different equipment easy.

Both types of IEC socket PDUs come in different sizes, depending on the number of outlets or sockets required. They also have different types of power cords and plugs to accommodate other power distribution requirements in various regions of the world.

The main difference between vertical and horizontal rack mount versions of IEC socket PDUs is their mounting orientation. The choice between the two depends on the specific requirements of your data centre or server room setup and the available rack space.