This is a plate that bolts between the oil pan and engine block. It is shaped to closly conform to the crank. As the crank rotates, it carries a lot of oil with it in a sort of tornado of oil. This plate scrapes the oil off the crank.
Acting as a crank scraper, the windage tray frees up horse power and puts oil back in the oil pan more quickly than gravity alone.
This oil pan windage tray also prevents the oil from climbing the block wall in left hand corners.
To install the oil pan tray you need to sandwich the tray in the middle of two oil pan gaskets.
For convenience, you can order a pair of gaskets with the tray, or just the tray by itself.