a few basic thoughts

Unlike the Canon Original the sun visor inside is neither matte nor (so as in the case Tamron usual) fluted. So it may be that in small scrap of light every now and then reflected from the inner edge of the aperture into the lens.
But I would like to say that the sun visor for Zoom Objekive anyway can not avoid every unnecessary light, because the edges of the sunshade always may only project so far forward as it will allow the outermost wide angle position of the respective lens. Otherwise there would be vignetting.
For this reason, one should of the effectiveness of a sun visor for a 15-85mm lens anyway not expect too much. Beyond the 15mm setting, the shutter can not completely block laterally incident light.
On the mechanical protection properties of a sun visor but that changes nothing of course.
I this respect also can not see how the Canon original should protect the lens from bumps better than the local JCC variant, I see no reason why you should spend the money for the extra cost.
So I would to anyone who is - despite the limitations mentioned - really wants to get a sun visor for its 15-85 mm, advise on this model here.

Both parts supplied from a processing perspective, the way to make a sufficiently good impression. As the plastic used but looks quite cheap, I give the result nevertheless "only" 4 stars.

The settlement of the purchase with the supplier Time Trends worked great.