This is a genuine replacement part that has been sourced from the original manufacturer to be used with lawn tractors. The metal deflector connects to the muffler assembly and is used to guide the direction of the exhaust gasses. This item is available as an individual replacement part. A hex socket wrench is required to install this item.
OEM stands for Original Equipment Manufacturer. Simply put, this means that the company who made your appliance is also supplying the replacement part for it.