Accounted for the largest percentage in the tea trade market in the world, according to the technological process OTD: fresh raw tea withering → fermentation jar → drying → clinical classification. Tea black brown red, the calm, mild flavor. After sifting, sorting (in the refining process) divided into several categories such as: OP, P, FBOP, OPA, TH, F, BPF, PS, BPS .... quality from high to low according to size side of tea to meet the needs of customers.