From Ubuntu11.04's help, it says: What is the meta key? The the meta key is key between the Ctrl and Alt keys on your keyboard. It may sometimes be called the windows key, logo key, system key, or even the Ubuntu key. If you have an Apple keyboard, there will not be a meta key on your keyboard. The Command (Cmd) key can be used instead. The meta key serves a special function in Unity. If you press the meta key, the Dash is displayed.
The main issue with the hoverboard is the battery. According to CNET, most hoverboards use lithium ion batteries, the kind often used in laptops and cell phones. But the liquid inside these batteries is flammable, and hoverboards (which have been produced and marketed out of thousands of essentially nameless factories in China) haven't adhered to a singular set of safety standards, and could very well be dangerous.
While a car battery is designed to deliver a burst of energy for a short time, a deep cycle battery provides power at a steady rate over a long period. There are different types of deep cycle batteries such as flooded batteries, gel batteries and AGM batteries (Absorbed Glass Mat); and more recently â lithium-ion.