Salesman will deliver/ship goods to customer along with external documents (delivery/invoice). This document will be stated the goods deliver to customers which is signed by approval (K.Suwat), deliver person, and receiver. In case of installment sale, customers will receive a membership letter (ใบแจ้งสมาชิกทราบ) which explaining about the payment period. Because installment sale is a transaction in which the sales price is paid in two or more installments over the years.