[Irregular Highly Feedback Keys]Irregular shape '+' and '+' Keys are magnified, helping you recognize what you pressed. The Special Keys make you have a different touch feeling on different keys, click sense of pressing a button makes your every press more accurate, and work more efficiently. [5' Ergonomic Tilted Display]5'' large LCD crystal-clear display. When you put the calculator on the desktop, the 30° large display is just opposite your sight, aligning perfectly with natural eye level for fatigue-free calculations. clearer than a horizontal display. [Dual Power & Auto Sleep]High-efficiency solar panel can be used in well-lit areas while the included AAA battery provides 18 months of backup power, doubling safe uninterruptible power. The calculator will shut down automatically after 8 minutes without operation. [High Quality ABS Engineering Plastic]This calculator is made of ABS high-strength engineering plastics, lightweight but durable. Reinforced button contacts rated for 1 mi