I wasn't sure - I've owned various high quality dies before (Knipex, Wiha etc) but I have to say they cut fasteners - flush zips. I just tossed them in my bag where I keep all the different lengths and sizes of zippers so they're there when I need them without having to look for them. Behind the blades is a small serrated area for zip tightening that seems to work well on lengths 14 inches and under.