People use magnets to "age" their wine. Apparently people also do this with whiskey and other beverages.
I think this magnet clips, is suppose to help "age" the wine as it passes through the spout of the bottle. Suppose to make the bitters taste more soft.
However, I did a quick Google search, and a double blind study showed; wine magnetized for 45min, did not change, or people still could not recognize or claim with consistency, that it did indeed make the wine taste better. Placebo effect I think.
By the way, if you like wine, Costco has a GREAT selection. Even the Kirkland brands are decent.