Mercury is a hazardous substance regulated by the Minamata Convention on Mercury. Many regions, including the EU (REACH/CE) and parts of the USA, have banned or strictly restricted the sale of mercury thermometers. You must confirm if your target market allows mercury-based instruments. If permitted, the product must have CE certification or FDA registration. Ensure the supplier provides a Material Safety Data Sheet (MSDS) and uses shatter-proof coating (like Teflon) to minimize leakage risks if the glass breaks.