Apple: use the product-specific lookup
Apple provides separate identification pages for iPhone, iPad, MacBook, and Apple Watch. For iPhone, Apple says to find the model number and look it up. For iPad, the model number identifies the model. About This Mac displays a Mac’s model name. In the Watch app, go to My Watch > General > About; tapping Model Number reveals an A-number identifier.
Samsung: search by code or product name
Samsung’s mobile-phone support page supports search by model code or product name and links to a “Find a model number” resource. Search using the information printed on your phone or its packaging.
Put the identifier in context
When you send a request, include both a familiar product name and the identifier when available. The form separately collects brand, model, condition, quantity, ZIP code, and a contact method.