一项法规，它通过对某种来自国外的产品和服务给予限制或者征税来保护同类的国内产品和服务。

Legislation that protects a given category of domestic product or service by imposing restrictions or levying taxes on them when they come from foreign sources.

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在国内市场销售上述进口材料生产的产品时海关征税只收取税率的50%，期限可延长至180天。

When sell products, which are produced by using of above mentioned import materials, the customs taxation will be paid only 50% of the rate, the period can be extended to 180 days.

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