Cm This is the production model of Chow Tai Fook products. It is the number of internal cycles from their internal design and production to listing. The difference is that cm is a Hong Kong version and zm is a mainland version. So cm means version. Just like some cosmetics, the same product has different numbers. Finally, the beginning of cm is that design, manufacturing, production and sales are all in Hong Kong, and the same as zm is that design, manufacturing, production and sales are all in the mainland. Before the counter is sold, signs such as cm zm will be affixed to facilitate management and identification. For example, if there are quality problems, you can find the place of origin according to these signs, and let the manufacturers correct the problems themselves, so that the quality of products can be improved every time, and consumers can buy with greater confidence.