DW corner cover plate (box of two) 58399
Ordering a quantity of 1 will get you a box of two corner top plates (where the green corner category header magnets will go).
Apprx 29"W x 9"T (735mm x 225mm)
You will also need one 9" extension (61684) per standpipe. Don't forget, a corner bay utilizes three standpipes.