Lexmark is dedicated to ensuring that its customers are purchasing and using genuine Lexmark supplies. By entering the 12 digit code (starting with CA) found on a toner cartridge, the authenticity of the cartridge can be verified. The serial number can be found on the outer box, as well as on the cartridge. Most Lexmark toner cartridge packaging also features a holographic security label that features a QR code and a label ID number. This label ID number can also be entered in the window below for authentication.