I love swiffer dusters, so I made this up when I got sick of buying new refills all the time.
These are washable and reusable til the cows come home, (I'm still using the original ones I made) and really easy to make, so be a little more green today and make a some for yourself. I've made them with fleece, but 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.
Cut 2 8x8 inch pieces of fleece or microfiber and 2 4x6 pieces.
Sew one small piece to each large piece. Stack them with the small pieces on the outside.
Push the small pieces to one side and sew the large pieces together around the center with a 1 1/4 x 6 inch slot
Slide the holder inside and snip all around the edges.