Extra Large Display: Larger display makes more data easier to read. Solar & Battery: Solar powered when light is sufficient, battery powered when light is insufficient. Silent Touch Keys: Keys are specially designed for silent operation when compared to previous CASIO calculators to help maintain a more pleasant working environment. Key Cap Shape: Keys are produced by injecting plastic of two different colours. Key markings are plastic, which means they do not wear or fade with use. Durable Anti-Fade Keys: Keys are ergonomically shaped and configured to match natural finger movements. Non-slip Structure: Large rubber feet on the bottom of the calculator keep it from slipping during operation.