Black Coloured Nickel Free Open and Closed End No.5 Zips. This range of metal open ended zips comes in a really useful range of lengths to suit whatever project you have on. They are strong and perfect to use on heavier materials. These nickel free zips are great for people who suffer from allergies and they also have shiny silver coloured metal teeth which may also suit your sewing project. These zippers are made of heavy duty metal.