Features: The 991ES Solar Scientific Calculator features friendly solar power technology, ensuring energy efficiency and long timeuse without frequent battery changes. The scientific calculator enables you to easily solve most complex math problems, equations, and scientific formulas, making it essential tool for students and professionals alike. it features a double power system with solar cell for extended use without batteries, and a battery backups for weeks of reliables performances. Equipped with a large, clear display and intuitively button layout,supports a wide ranging of scientific functions like trigonometry, logarithms, and exponent, making complex calculations straightforward. Widely used for students across all grades, especially high school and college, as well as teachers, researcher, and office professional who require precise and reliabled calculation tool. Specifications: Product size: about 150x80x50mm/5.91x3.15x1.97inch Material: ABS Model：991ES Color: as shown in the picture Package Includes: 1PC Solar Scientific Calculator note: Due to problems of lighting effects, there might be tolerances in product, please understand. Please allow 0-1cm error due to manual measurement.