... for example,the metal,the nylon and the resin.certificate:ISO9001:2000 Excellent credit enterpriseSpecifications:1) Available types: 3#, 4#, 5#, 7#, 8 ... style better and better.Detials of the zippers:Brand name:yooModel:VariousSize:3#, 4#, 5#, 7#, 8#, 10# or Custom ... made any size according to your requirementsQuality:ReasonablePrice:the lowestProduct feature:Eco-friendly ...