1. Durable double coil zipper is sewing two chains up and down side on single tape. The combination of these two chains are strong that won't be force open by sharp things. Sewing small bands together upon bottom chain to protect sewing threads and avoid sewing threads to be scratched by slider. Special designed slider for durable double coil zipper. The top part of this slider is longer than bottom. When slider moves on the chains around the corner, it could be stable and smooth. It won't forced open. 2. Target Market: Luggage & Backpack/ Cash transport bags/ Tent/ Sleeping Bag/ Outdoor ceiling/ Covered fabric for boats/ Military 3. Technology Because the angles of two layers of the teeth combination are different, the normal slider can't work well in durable double coil zipper. The slider body can't restrain both side of teeth, then will make teeth burst in one side. To solve this problem, KCC designs a special slider for durable double coil zipper. The top part of slider is longer than bottom. It makes sliding stable and smooth around the corner, and won't be forced open. The spiral teeth of polyester zipper is sewed on the tape by sewing thread. As this reason, sewing thread is protruded on the teeth surface, and it would be scratched by slider easily, especially in the corner of luggage or bag. When the sewing thread is hurt by slider seriously, the teeth will separate from tape and the zipper can't work anymore. It means the luggage is damaged already. To solve this problem, KCC use small bands sewn on bottom teeth to protect sewing thread. Slider won't scratch the sewing thread directly to avoid the risk of zipper damaged.