At the corners, the width on the long side is 5-7/8 edge to edge and in the center is 6-1/4( side to side) and on the shorter side (top to bottom) it is 4-7/8 at the corner and 5-1/8 in the center. Will not cover a 6" x 6" opening.
Nope. Won't cover a 6" x 6" hole. It's made to cover a 4-square electrical box. The plate itself measures 4 3/4" high X 6" wide, measured at it's widest dimension. It's not a rectangle. (Kinda rounded.) Hope this helps.
4.5 X 6
Roughly 5" high, 6" wide
From the info I have it will not fit the TH5220's.