UL is the abbreviation of underwriter Laboratories Inc.; UL can also be the logo and standard of the company and safety regulations. UL safety test institute is the most authoritative civil institution in the United States, which is also engaged in safety test and appraisal. It is an independent, not-for-profit, professional organization that conducts experiments for public security. It uses scientific testing methods to study and determine whether various materials, devices, products, equipment, buildings, etc. are harmful to life and property; it determines, compiles and issues corresponding standards and materials that are helpful to reduce and prevent the loss of life and property, and it also carries out factual research. It is mainly engaged in product safety certification and operation safety certification business. Its ultimate purpose is to obtain goods with a considerable level of safety for the market, and to make contributions to the guarantee of personal health and property safety.

Cul is to add CSA (Canada) certification on the basis of UL, and obtain the common safety certification mark of the United States and Canada.