The logo number is four digits, such as Menghai Factory 7572 and 7542, Kunming Factory 758 1, Xiaguan 8653 and 8853.

The first two digits indicate the invention date of the formula, the third digit indicates the teapot series, and the fourth digit indicates the tea factory.

Not all the marks are printed on the wrapping paper. In recent years, many products are printed on the wrapping paper of tea cakes, but most of the early products are not printed on the wrapping paper, usually on large bills, attached to the outer packaging of the whole goods or printed on the outer packaging of the whole barrel of bamboo shoots. If you just buy a single item, you can't see it.