These mugs typically have a built-in mechanism at the bottom that rotates to stir the contents of the mug when activated. They're quite handy for mixing coffee, tea, or any other beverages without the need for a separate stirring utensil.

The "MAVDI Self Stirring Coffee, Stainless Steel Automatic Self Mixing & Spinning Cup" you mentioned appears to be one such product. Here are some features you might expect from it :  

Stainless Steel Construction : This ensures durability and makes the mug suitable for both hot and cold beverages.

Self-Stirring Mechanism : The mug likely has a button or switch that, when activated, causes a small motor at the bottom to spin, stirring the contents of the mug.

Convenience : These mugs are convenient for individuals who don't want to bother with manually stirring their drinks or carrying separate stirring utensils.

Battery-powered : Most self-stirring mugs are powered by batteries, typically AA or AAA, which are easy to replace when needed.

Capacity : The capacity of the mug can vary, but it's typically around 12-16 ounces, suitable for a standard serving of coffee or tea.

Easy to Clean : Many self-stirring mugs are designed for easy cleaning, with detachable components that can be washed separately from the electronic parts.