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.
3 of the most common chemistry types of batteries used in garden solar lights are NiMH (Nickel Metal Hydride), NiCd (Nickel Cadmium) and Lithium Ion. The most common sizes (and the ones we carry at Your Solar Link) are AA rechargeable batteries and AAA rechargeable batteries. The range in capacity (mAh, or milliAmp hours) can run from 300 mAh on up to 1200 mAh. The most commonly used capacities in solar garden lights are 300 mAh, 600 mAh and 1000 mAh.