The surface-mount bracket allows enough space behind the MATE3 that the CAT5 cable can be brought directly into the MATE3 without routing the cable through a wall. In addition, the bracket can be attached to an existing mounting plate, such as the OutBack FLEXPower ONE assembly. This is usually only done when a bracket is being replaced. 
NOTE: The cable can be routed into the back of the mounting bracket through an opening in the wall or surface. This cabling method can be used if the cable must be concealed inside a wall or brought from one room to another.