Flat bottom bag also can be a kind of zipper bag. There are two types of zipper that we recommend to you. The first one is the ordinary zipper,is a zipper choice for the vest majority people; and another kind of the zipper is tear more easier than the first one,and the zipper’s buckle is a shape like a butterfly. The way to open it is squeeze the butterfly buckle then pull tab to open.

What more, the bag with this type of zipper,the opening of the bag is bigger than others,and is more convenient when you are filling the content into the bag. There is one more place is different to the general zipper bag. The different place is during the production process, this kind of bag will use hot air to press a valve. There has a valve into the bag !

So ,what is the purpose of the valve? As an example, when the coffee beans are freshly roasted and packaged, the beans will release carbon dioxide gas at this time. This gas will continue to be released until the end of packaging. When the packaging is finished, the carbon dioxide still stay in the bag, and there will be the situation of rising packaged. At this time, the function of the  valve is reflected. You can open the valve of the packaging bag to exhaust. Because the valve is one-way exhaust, there is no need to worry that the gas outside the packaging bag will enter. There is a valve can also play a role in preventing moisture.