The Aurora EC505 desk EcoCalc, is made from recycled plastic, powered entirely by light and is totally battery free. It has a large 12 digit LCD display for easy viewing, hard plastic keys and large numerals for ease of use and Aurora's patented long equals bar to enable speedy calculations. The handy Cost-Sell-Margin function is great for sales and gross profit calculations and the patented DirecKey feature means that this calculator turns on when any key is pressed, this key stroke will also register. So overall a great calculator that combines functionality with eco-friendly features.