Gives the phrase no-see-um a new meaning.
Invisible Zipper: A zipper with its teeth hidden behind fabric tape, which matches the garment's color as does the slider. Then, except for the slider the zipper is "invisible". This is common in women's wear, and some newer packs. The zipper mechanism is usually a coil zipper, which doesn't bite so hard if you get your whodunit caught in it.