This is a reverse Polish notation (RPN) scientific calculator. It's discontinued now, so it might be difficult to find. A Japanese manual is included, so you can learn while using it. It was originally used with the genuine case, but the case deteriorated due to hydrolysis and is now missing. It's an old item, so there are some scratches, but it works without any problems. Thank you for your consideration. - Model: HP 35s - Type: Scientific Calculator - Language: Japanese user guide included - Functions: Trigonometric functions, statistics, logical operations, etc. - Country of manufacture: China