If anyone has ever wondered what the difference is between the MMF2 and MMF3, 4/3 to m4/3 adapter, well, not much really. I have both and from what I can tell, the only difference is that the MMF3 has weather sealing, where the MMF2 does not. And for some reason, the MMF2 appears more substantial than the MMF3. It's a tad heavier, giving it the feel of being more robust, for what that may be worth. Both focus just as fast on the E-M1 at least. So if you're ever contemplating buying a 4/3 to m4/3 adapter, if you don't intend to work in pouring rain etc, then the cheaper MMF2 will serve you well.