When a consumer purchases a certain number or amount of products, the manufacturer will offer additional gifts of similar or related products according to a certain percentage or requirement. "Buy one, get one free" is the most common way of additional gifts, consumers spend a product money can get two products, equivalent to enjoy 50% discount, the essence or discount strategy. This method can not only effectively stimulate consumers to buy, and can help accelerate the promoter to complete the sales target. Commonly used in the unit price is lower, simple packaging, the use of the frequency of daily consumer goods faster.