I received the Catiga 12 digit dual power calculator for free in exchange for my honest review. This is a nice small desktop calculator. First thing I noticed was the weight--it's heavier than many others of its size, may be a sturdier case. This makes it 'stick' better on the desk so it doesn't push around while using it, and it has rubber feet to help that too. It's 4.5" wide by 6" high, with an angled display, numbers are about 3/4" high, and easily readable. It has a "00" button, which lets you put two zeros after the 1st number every time you push it, for those who need lots of zeros faster. Buttons are nice size, work very well, don't have that cheap 'rattle' some of the cheaper ones do. Has auto shut-off after "5-12 minutes", that works, but seems a bit longer than necessary to me. A dedicated 'off' button would be nice, like many of the $1 calculators have these days. Battery is changeable, takes one AG13/LR44. Solar power works fine under a desk lamp. Comes with a small instruction manual that basically just shows you calculations and what buttons to push for them, not much text to explain things. Seems to be a quality unit, so recommended.