This end plate allows you to mount it on 30mm spacing mounts. Also retains holes for 25mm spacing mounts.
When removing the bearings from the original end cap, they can sometimes be damaged. WFO advises purchasing a new bearing to install in the wfo end cap when you install it.
Bearing is available here- https://wforccustoms.com/products/hobbywing-4985-1650kv-motor-bearing