ReadWrytOlympus makes Micro 4/3s lenses, which are compatible with Olympus and Panasonic bodies. They don’t make Canon or Nikon mount lenses, and no longer make 35mm cameras or lenses. Sure, MassDrop could have denoted that in the description, but it’s pretty obvious.
It is common to list the conversion to 35mm to give a frame of reference to traditional zoom ranges.
ReadWrytListing the equivalency is just a convention in the m4/3 world. Everyone else does it too. But yeah, I agree the listing should say micro four thirds. I've been shooting m4/3 for 8 years. I know the lenses. I was looking for some mention of micro four thirds too just to confirm what *seemed* obvious. I'm not worried about *me* not understanding; I'm worried that whoever wrote the listing wasn't paying attention, didn't know the product, and missed other details too.