This is a Hewlett-Packard function calculator. It's a model known for its financial calculation functions and Reverse Polish Notation (RPN) operation, popular in the financial industry. It operates on one CR2032 button battery. The case of this item has been cleaned. I have performed basic calculations and confirmed that the operation is working without issues. I have also run a self-test and confirmed that the display is working correctly. However, I have not confirmed that all functions are working perfectly. Please examine the photos carefully, as the exterior of the main unit has minor scratches and dirt. There is no instruction manual. It is currently working, but due to its age, I cannot guarantee its operation after shipping. Please feel free to ask any questions before purchasing if you have any concerns.