Each duster has a 4 layer thickness of fleece. The best thing I've noticed about using these dusters is they don't flatten out like the disposable ones do, so they actually last longer. And don't forget the fact that they are washer and dryer safe (with out fabric softener)
Make your own "Better than Swiffer" Dusters. Microfiber seems to work best, it really grabs the dust. You can usually finds sheets of it in the car cleaning section. You can also easily make swiffer mop covers too, by just measuring a rectangle about twice as long as the mop, folding over the ends to fit it and sewing them in place.
DIY Reusable Swifter Duster Covers - a MUST if you dust :) I actually like these better then the disposable ones plus they save tons of $ and are better for the environment! Click the photo to see the Tutorial!