My 220 insert. Should be the same, but my 120 is in camera with film...sorry.
The frame is 2 7/8" wide plus some slide pins (tabs) that hold it in place when you let go of the pinch release handle thingy. I would say 3 1/16" with the tabs.
1 5/8" (+about 1/64th") front to back.
a little less than 2 5/16" tall from bottom roll to top roll.

Opening in camera is:
1/64" less than 3" wide
2 9/16" tall
Cant measure depth with plastic ruler...can get micrometer later.

Sorry for the non metric dimensions.....I'm an american.