Invisible zippers are the least noticable of all zippers. As the name implies, the zipper is hidden in a seam, becoming virtually invisible. This makes it a popular choice for elegant clothing sewn with expensive materials, like evening w ear. But it’s equally appropriate for skirts, blouses and other everyday clothing items. Invisible zippers (also called concealed zippers)are easily sewn with the Pfaff Invisible Zipper Foot! This foot fits most models of Pfaff machines, except for the older 300 and 900 series, the 6085/86/87 models, anc the 1020/30/40 series of machines.