This is an old Hewlett-Packard programmable scientific calculator. It's characterized by its Reverse Polish Notation (RPN) operation. It runs on three LR44 button cell batteries. This item has had its case cleaned, and I've confirmed that it performs basic calculations correctly and that there are no operational issues. I've also run a self-test and confirmed that the display is working properly. However, I haven't verified that all functions are working perfectly. The metal panel of the main unit shows noticeable discoloration. There are also other minor scratches and stains, so please examine the photos carefully to check the condition. A dedicated pouch is included with the main unit. It is currently working, but as it is an old item, I cannot guarantee its operation after shipping. If you have any concerns, please feel free to comment before purchasing.