The Seafrog housing says in it's specs "both 52 AND 67mm lens thread" but I see no evidence of this on a close-up photo of the housing. I see only 52mm thread, same as the Olympus. It does not come with an adapter ring, so I don't see how the Seafrog can make that claim. (it even clearly says "52mm" on the red aluminum lens opening ring in the photo).
See the photos here and here - inner ring is 52mm, outer ring is 67mm.