1, one-way exhaust valve coffee bags on top of the package and the bag surface Zakon package check valve position, will be able to separate out carbon dioxide baked beans automatically discharged out of the bag after the outside air can not enter the bag . Effectively guarantee the beans dry and mellow flavor, not because of the accumulation of carbon dioxide in order to open up the bag to prevent contamination within the packaging deterioration by oxidation. Mainly used bag storage bags, storage bags, feed bags and other needs of the flexible packaging gases revealing way. 2, since the plastic bags set above the one-way exhaust valve, fully loaded bags in the stacking process, the body of the residual air in the bag in the lower part of the upper portion of the packaging bag under gravity from the way goods discharge valve, can improve the stability of the stack, the stack height increases. 3, to improve the impact resistance of plastic bags, when filled with goods bags during transport or falls from a height, the air bag from the unidirectional discharge valve, reducing the shock wave generated by the residual air bag reduce or avoid the resulting broken packages. I produced a one-way valve is made of food-grade PE materials, the products have been 100% tested, stable and reliable quality, welcomed the order.