This duo cam type zoom barrel is illustrated with the following two pictures: There are three versions of this lens.
[1] The second version (from 1999 to 2002) featured an improved 7 blade aperture, same 15 elements in 12 groups optical formula, with metal replacing plastic on many of the zoom components and "MACRO" instead of a flower marking the side.
The third version (from 2003 to 2010) was manufactured and assembled in Taiwan with a 7 blade aperture, MACRO on the side, a textured case, "II" added to the description on the bezel.
These are two inexpensive versions of the 28–105mm, cosmetically similar to the EF-S 18–55mm or the 90–300mm lenses which have the characteristic rubber grip on the barrel.
[3] While retailing for around $100 less, these lenses have a decreased f-stop range and cheaper build quality (with a chrome-plated ring).